question, how many vegetable forms—leafless cryptogamia (water algæ,
fungi, and lichens), characeæ, liverworts, foliaceous mosses,
marsilaceæ, lycopodiaceæ, and ferns—exist on the dry land, and in the
wide basin of the sea, in the present condition of the organic
terrestrial life of our planet, it only remains for us to employ an
approximative method for ascertaining with some degree of probability
certain “extreme limits” (numerical data of minima). Since the year
1815, I have, in my arithmetical considerations on the geography of
plants, calculated the numbers expressing the ratio which the
aggregate of species of different natural families bears to the whole
mass of the phanerogamia in those countries where the latter is
sufficiently determined. Robert Brown,[NE] the greatest botanist of
our age, had, prior to my researches, already determined the numerical
proportion of the principal divisions of vegetable forms, as for
instance of acotyledons (_Agamæ_, cryptogamic or cellular plants) to
cotyledons (_Phanerogamia_, or vascular plants), and of monocotyledons
(_Endogenæ_) to dicotyledons (_Exogenæ_). He finds the ratio of
monocotyledons to dicotyledons in the tropical zone as in the
proportion of 1 to 5, and in the frigid zone, in the parallels of 60°
north, and 55° south lat. as 1 to 2½.[NF] The absolute numbers of the
species are compared together in the three great divisions of the
vegetable kingdom, according to the method developed in Brown’s work.
I was the first who passed from these principal divisions to the
individual families, and considered the number of the species
contained in each, in their ratio to the whole mass of phanerogamia
belonging to one zone.[NG]
The numerical relations of the forms of plants, and the laws observed
in their geographical distribution, admit of being considered from two
very different points of view. When we study plants in their
arrangement according to natural families, without regard to their
geographical distribution, the question arises: What are the
fundamental forms or types of organization, in accordance with which
the greater number of their species are formed? Are there more
Glumaceæ than Compositæ on the earth’s surface? Do these two orders of
plants combined, constitute one-fourth of the phanerogamia? What
numerical relation do monocotyledons bear to dicotyledons? These are
questions of general phytology, a science that investigates the
organization of plants and their mutual connection, and therefore has
reference to the now existing state of vegetation.
If, on the other hand, the species of plants that have been connected
together according to their structural analogy, are considered not
abstractedly, but in accordance with their climatic relations, and
their distribution over the earth’s surface, these questions acquire a
totally different interest. We then examine what families of plants
predominate in the torrid zone more than towards the polar circle over
other phanerogamia? We inquire, whether the Compositæ are more
numerous in the new than in the old world, under equal geographical
latitudes or between equal isothermal lines? Whether the forms which
gradually lose their predominance in advancing from the equator to the
poles, follow a similar law of decrease in ascending mountains
situated in the equatorial region? Whether the relations of the
different families to the whole mass of the phanerogamia differ under
equal isothermal lines in the temperate zones on either side of the
equator? These questions belong to the geography of plants properly so
called, and are connected with the most important problems that can be
presented by meteorology and terrestrial physics. Thus the
predominance of certain families of plants determines the character of
a landscape, and whether the aspect of the country is desolate or
luxuriant, or smiling and majestic. Grasses, forming extended
Savannahs, or the abundance of fruit-yielding palms, or social
coniferous trees, have respectively exerted a powerful influence on
the material condition, manners, and character of nations, and on the
more or less rapid development of their prosperity.
In studying the geographical distribution of forms, we may consider
the species, genera, and natural families of plants separately. A
single species, especially among social plants, frequently covers an
extensive tract of land. Thus we have in the north, Pine or Fir
forests, and Heaths (_ericeta_); in Spain, Cistus groves; and in
tropical America, collections of one and the same species of Cactus,
Croton, Brathys, or Bambusa Guadua. It is interesting to study more
closely these relations of individual increase, and of organic
development; and here we may inquire, what species produces the
greatest number of individuals in one certain zone; or, merely what
are the families to which the predominating species belong in
different climates. In a very high northern latitude, where the
Compositæ and the Ferns stand in the ratios of 1 : 13 and 1 : 25 to
the sum of all the phanerogamia (_i. e._, where these ratios are found
by dividing the sum total of all phanerogamia by the number of species
included in the family of the Compositæ, or in that of the Ferns); one
single species of Fern may, however, cover ten times more space than
all the species of the Compositæ taken together. In this case the
Ferns predominate over the Compositæ by their mass, and by the number
of the individuals belonging to the same species of Pteris, or
Polypodium; but they will not be found to predominate, if we only
compare the number of the different specific forms of the Filices, and
of the Compositæ, with the sum total of all Phanerogamia. As,
therefore, multiplication of plants does not follow the same laws in
all species, and as all do not produce an equal number of individuals,
the quotients obtained by dividing the sum of all phanerogamic plants
by the species of one family, do not _alone_ determine the leading
features impressed on the landscape, or the physiognomy of nature
peculiar to different regions of the earth. If the attention of the
travelling botanist be arrested by the frequent repetition of the same
species, by its mass, and the uniformity of vegetation thus produced,
it will be still more forcibly arrested by the infrequency of many
other species useful to man. In tropical regions, where the Rubiaceæ,
Myrtles, Leguminosæ, or Terebinthaceæ, compose the forests, one is
astonished to meet with so few trees of Cinchona, or of certain
species of mahogany (_Swietenia_), of Hæmatoxylon, Styrax, or balsamic
Myroxylon. I would also here refer to the scanty and detached
occurrence of the precious febrifuge-bark trees (species of Cinchona)
which I had an opportunity of observing on the declivity of the
elevated plains of Bogota and Popayan, and in the neighbourhood of
Loxa, in descending towards the unhealthy valley of the Catamayo, and
to the river Amazon. The _febrifuge-bark hunters_ (Cazadores de
Cascarilla), as those Indians and Mestizoes are called at Loxa, who
each year collect the most efficacious of all the medicinal barks, the
_Cinchona Condaminea_, among the lonely mountains of Caxanuma,
Uritusinga, and Rumisitana, undergo considerable danger in climbing to
the summits of the highest forest-trees, in order to obtain an
extended view, from which they may distinguish the scattered, slender,
and aspiring trunks of the Cinchona, by the reddish tint of their
large leaves. The mean temperature of this important forest region
(between 4° and 4½° south lat.) varies from 60° to 68° Fahr., at an
absolute height of from 6400 to 8000 feet above the level of the
sea.[NH]
In considering the distribution of species, we may also, independently
of individual multiplication and mass, compare together the absolute
number which belong to each family. Such a mode of comparison, which
was employed by Decandolle,[NI] has been extended by Kunth to more
than 3300 of the species of Compositæ with which we are at present
acquainted. It does not show what family preponderates by individual
mass, or by the number of its species, over other phanerogamic forms,
but it simply indicates how many of the species of one and the same
family are indigenous in any one country or portion of the earth. The
results of this method are, on the whole, more exact, because they are
obtained by a careful study of the separate families, without
requiring that the whole number of the phanerogamia of every country
should be known. Thus, for instance, the most varied forms of Ferns
are found in the tropical zone, each genus presenting the greatest
number of species in the temperate, humid, and shaded mountainous
parts of islands. While these species are less numerous in passing
from tropical regions to the temperate zone, their _absolute number_
diminishes still more in approaching nearer to the poles. Although the
frigid zone, as, for instance, Lapland, supports species of the
families which are best able to resist the cold, Ferns predominate
more over other phanerogamia in Lapland than either in France or
Germany, notwithstanding the absolute inferiority of the gross number
of ferns indigenous to the northern zone, when compared with other
countries. These relations are, in France and Germany, as ¹⁄₇₃ and
¹⁄₇₁, while in Lapland they are as ¹⁄₂₅. These numerical relations
(obtained by dividing the sum total of all the phanerogamia of the
different floras by the species of each family) were published by me
in 1817, in my _Prolegomena de distributione geographica Plantarum_,
and corrected in accordance with the great works of Robert Brown, in
my Essay on the Distribution of Plants over the earth’s surface, which
I subsequently wrote in French. These relations, as we advance from
the equator towards the poles, necessarily vary from the ratios
obtained by a comparison of the absolute number of the different
species belonging to each family. We often see the value of the
fractions increase by the decrease of the denominator, whilst the
absolute number of the species is reduced. In the fractional method
which I have followed as the most applicable to questions relating to
the geography of plants, there are two variable quantities; for in
passing from one isothermal line to another, we do not find the sum
total of the phanerogamia change in the same proportion as the number
of the species of one particular family.
In proceeding from the consideration of these species to that of the
divisions established in the natural system according to an ideal
series of abstractions, we may direct our attention to genera or
races, to families, or even to still higher classes of division. There
are some genera, and even whole families, which exclusively belong to
certain zones; not merely because they can only thrive under a special
combination of climatic relations, but also because they first sprang
up within very circumscribed localities, and have been checked in
their migrations. The larger number of genera and families have,
however, their representatives in all regions of the earth, and at all
elevations. The earliest inquiries into the distribution of vegetable
forms had reference to genera alone, and are to be found in the
valuable work of Treviranus.[NJ] This method is, however, less
appropriate for yielding general results, than that which compares the
number of the species of each family, or the great leading divisions
(acotyledons, monocotyledons, and dicotyledons), with the sum total of
the phanerogamia. In the frigid zone, the variety of forms, or the
number of the genera, does not decrease in an equal degree with that
of the species, there being in these regions relatively more genera
and fewer species.[NK] The case is almost the same on the summits of
high mountain-chains, where are sheltered individual members of many
different genera which one would be disposed to regard as belonging
exclusively to the vegetation of the plain.
I have deemed it expedient to indicate the different points of view
from which the laws of the distribution of vegetable forms may be
considered. It is only when these points of view are confounded
together, that we meet with contradictions, which have been unjustly
attributed to uncertainty of observation.[NL] When expressions like
the following are employed: “This form, or this family diminishes as
it approaches towards the cold zone,” or “the true habitat of this
form is in such or such a parallel of latitude;” or “this is a
southern form,” or, again, “it predominates in the temperate zone;” it
should be definitely stated whether reference is made to the absolute
number of the species, and the proportion of their predominance
according to the increase or decrease of latitude; or whether the
meaning conveyed is, that a family, when compared with the whole
number of the phanerogamia of a flora, predominates over other
families of plants. The impression conveyed to the mind of the
predominance of forms, depends literally on the conception of relative
quantity.
Terrestrial physics have their numerical elements as well as the
cosmical system, and it is only by the united labours of botanical
travellers that we can hope gradually to arrive at a knowledge of the
laws which determine the geographical and climatic distribution of
vegetable forms. I have already observed that in the temperate zone of
the northern hemisphere, the Compositæ (Synanthereæ) and the Glumaceæ
(in which latter division I place the three families of the Gramineæ,
the Cyperoideæ, and the Juncaceæ) constitute the fourth part of all
phanerogamia. The following numerical relations are the result of my
investigations for seven great families of the vegetable kingdom in
one and the same temperate zone:
Glumaceæ ⅛ (Grasses alone ¹⁄₁₂)
Compositæ ⅛
Leguminosæ ¹⁄₁₈
Labiatæ ¹⁄₂₄
Umbelliferæ ¹⁄₄₀
Amentaceæ (Cupuliferæ, Betulineæ, and
Salicineæ) ¹⁄₄₅
Cruciferæ ¹⁄₁₉
The forms of organic beings are reciprocally dependent on one another.
Such is the unity of nature, that these forms limit each other in
obedience to laws which are probably connected with long periods of
time. When we have ascertained the number of the species on any
particular part of the earth’s surface belonging to one of the great
families of the Glumaceæ, the Leguminosæ, or the Compositæ, we may
with some degree of probability, form approximative conclusions
regarding the number of all the phanerogamia, as well as of the
species belonging to the other families of plants growing in the
country. The number of the Cyperoideæ determines that of the
Compositæ, and the number of the latter determines that of the
Leguminosæ; and these estimates, moreover, enable us to ascertain in
what classes and orders the Floras of a country are still incomplete,
teaching us what harvests may still be reaped in the respective
families, if we guard against confounding together very different
systems of vegetation.
The comparison of the numerical proportions of families in the
different zones which have as yet been well explored, has led me to a
knowledge of the laws which determine the numerical increase or
decrease of vegetable forms constituting a natural family, in
proceeding from the equator to the poles, when compared, for instance,
with the whole mass of phanerogamia peculiar to each zone. We must
here have regard not only to the direction, but also to the rapidity
or measure of the increase. We see the denominator of the fraction,
which expresses the ratio, increase or diminish. Thus, for instance,
the beautiful family of the Leguminosæ diminishes in proportion as it
recedes from the equinoctial zone to the north pole. If we find its
ratio for the torrid zone (from 0° to 10° of latitude) ⅒, we shall
have for the part of the temperate zone (lying between 45° and 52°)
¹⁄₁₈, and for the frigid zone (between 67° and 70° lat.) only ¹⁄₃₅.
The direction followed by the great family of the Leguminosæ (viz.,
increase towards the equator) is also that of the Rubiaceæ, the
Euphorbiaceæ, and especially the Malvaceæ. On the other hand, the
Gramineæ and the Juncaceæ (the latter more than the former), the
Ericeæ, and Amentaceæ, diminish towards the torrid zone. The
Compositæ, Labiatæ, Umbelliferæ, and Cruciferæ, diminish from the
temperate zone towards the pole and the equator, and the two latter
families most rapidly in the direction of the equatorial region;
whilst in the temperate zone the Cruciferæ are three times more
abundant in Europe than in the United States of North America. In
Greenland the Labiatæ are reduced to only one species, and the
Umbelliferæ to two, while the whole number of the phanerogamia still
amounts, according to Hornemann, to 315 species.
It must at the same time be observed that the development of plants of
different families, and the distribution of their forms, do not depend
alone on the geographical, or even on the isothermal latitude; the
quotients not being always equal on one and the same isothermal line
in the temperate zone, as for instance in the plains of America and in
those of the Old Continent. Within the tropics there is a very marked
difference between America, the East Indies, and the western coast of
Africa. The distribution of organic beings over the surface of the
earth does not depend solely on the great complication of thermic and
climatic relations, but also on geological causes which continue
almost wholly unknown to us, since they have been produced by the
original condition of the earth, and by catastrophes which have not
affected all parts of our planet simultaneously. The large
pachydermata are no longer found in the New Continent, while they
still exist under analogous climates in Asia and Africa. These
differences, instead of deterring us from the investigation of the
laws of nature, should rather stimulate us to study them in all their
intricate modifications.
The numerical laws of families, the frequently striking agreement
between the ratios, where the species constituting these families are
for the most part different, lead us into that mysterious obscurity
which envelopes everything connected with the fixing of organic types
in the different species of animals and plants, and with all that
refers to formation and development. I will take as examples two
neighbouring countries—France and Germany—which have both been long
since explored. In France many species of Gramineæ, Umbelliferæ,
Cruciferæ, Compositæ, Leguminosæ, and Labiatæ are wanting, which are
some of the commonest in Germany, and yet the ratios of these six
large families are almost identical in both countries. Their
relations, which I here give, are as follows:
Families. Germany. France.
Gramineæ. ¹⁄₁₃ ¹⁄₁₃
Umbelliferæ. ¹⁄₂₂ ¹⁄₂₁
Cruciferæ. ¹⁄₁₈ ¹⁄₁₉
Compositæ. ⅛ ⅐
Leguminosæ. ¹⁄₁₈ ¹⁄₁₆
Labiatæ. ¹⁄₂₆ ¹⁄₂₄
This correspondence in the number of species of one family compared to
the whole mass of the phanerogamia of Germany and France would not
exist, if the absent German species were not replaced in France by
other types of the same families. Those who delight in conjectures
respecting the gradual transformation of species, and who regard the
different parrots, peculiar to islands situated near each other, as
merely transformed species, will ascribe the remarkable uniformity
presented by the above numerical ratios to a migration of the same
species, which having been altered by climatic influences, continuing
for thousands of years, appear to replace each other. But why have our
common Heath, (Calluna vulgaris,) and our Oaks not penetrated to the
east of the Ural Mountains, and passed from Europe to northern Asia?
Why is there no species of the genus Rosa in the southern, and
scarcely any Calceolaria in the northern hemisphere? These are points
that cannot be explained by peculiarities of temperature. The present
distribution of forms (fixed forms of organization) is no more
explained by thermal relations alone, than by the hypothesis of
migrations of plants radiating from certain central points. Thermal
relations are scarcely sufficient to explain the phenomenon why
certain species have fixed limits beyond which they cannot pass,
either in the plains towards the pole, or in vertical elevation on the
declivities of mountains. The cycle of vegetation of each species,
however different may be its duration, requires a certain minimum of
temperature to enable it to arrive at the full stage of its
development.[NM] But all the conditions necessary to the existence of
a plant, either within its natural sphere of distribution or
cultivation—such as geographical distance from the pole, and elevation
of the locality—are rendered still more complicated by the difficulty
of determining the beginning of the thermic cycle of vegetation; by
the influence which the unequal distribution of the same quantity of
heat among days and nights succeeding each other in groups, exerts on
the irritability, the progressive development, and the whole vital
process; and lastly, by the secondary influence of the hygrometric and
electric relations of the atmosphere.
My investigations regarding the numerical laws of the distribution of
vegetable forms may, perhaps, at some future time, be applied
successfully to the different classes of vertebrate animals. The rich
collections of the Muséum d’histoire naturelle in the Jardin des
Plantes at Paris, contained in 1820, at a rough estimate, above 56,000
species of phanerogamic and cryptogamic plants in the herbariums,
44,000 insects (probably below the actual number, although they were
thus given me by Latreille), 2500 species of fishes, 700 reptiles,
4000 birds, and 500 mammalia. Europe possesses about 80 mammalia, 400
birds, and 30 reptiles; there are, therefore, five times as many birds
as mammalia in the northern temperate zone, (as there are in Europe
five times as many Compositæ as Amentaceæ and Coniferæ, and five times
as many Leguminosæ as Orchideæ and Euphorbiaceæ). In the southern
temperate zone the ratio of the Mammalia bears a sufficiently striking
accord with that of Birds, being as 1 : 4·3. Birds (and reptiles even
to a greater extent), increase more than mammalia in advancing towards
the torrid zone. We might be disposed to believe, from Cuvier’s
investigations, that this ratio was different in the earlier age of
our planet, and that the number of mammalia that perished by
convulsions of nature was much greater than that of birds. Latreille
has shown the different groups of insects that increase in advancing
towards the pole, or towards the equator, and Illiger has indicated
the native places of 3800 birds, according to the quarters of the
globe;—a far less instructive method than if they had been given
according to zones. We may easily comprehend how, on a given area, the
individuals of one class of plants or animals may limit each other’s
numbers, and how, after the long-continued contests and fluctuations
engendered by the requirements of nourishment and mode of life, a
condition of equilibrium may have been at length established; but the
causes which have determined their typical varieties, and have
circumscribed the sphere of the distribution of the forms themselves,
no less than the number of individuals of each form, are shrouded in
that impenetrable obscurity which still conceals from our view all
that relates to the beginning of things and the first appearance of
organic life.
If, therefore, as I have already observed at the beginning of this
illustration, we attempt to give an approximative estimate of the
_numerical limit_ (“le nombre limite” of the French mathematicians),
_below_ which we cannot place the sum of all the phanerogamia on the
surface of the earth; we shall find that the surest method will be by
comparing the known ratios of the families of plants with the number
of the species contained in our herbariums, or cultivated in large
botanical gardens. As I have just remarked, the herbariums of the
Jardin des Plantes at Paris were, in 1820, already estimated at 56,000
species. I will not hazard a conjecture as to the number that may be
contained in the herbariums of England, but the great Paris herbarium,
which Benjamin Delessert with the noblest disinterestedness has given
up to free and general use, was estimated, at the time of his death,
to contain 86,000 species, a number almost equal to that which
Lindley, even in 1835,[NN] regarded as the probable number of all the
species existing “on the whole earth.” Few herbariums are numbered
with care, according to a complete, severe, and methodical separation
of the different varieties; while, moreover, we often find no
inconsiderable number of plants wanting in the large so-called general
herbariums, which are contained in some of the smaller ones. Dr.
Klotzsch estimates the whole number of Phanerogamic plants in the
Great Royal Herbarium at Schöneberg, near Berlin, of which he is
curator, at 74,000 species.
Loudon’s useful work (_Hortus britannicus_) gives a general view of
the species which now are or recently have been, cultivated in English
gardens. The edition of 1832 enumerates, including indigenous plants,
exactly 26,660 Phanerogamia. We must not confound with this large
number of plants that either have been, or still are, cultivated in
Great Britain, “all the living plants which may simultaneously be
found in an individual botanic garden.” In this last respect the
Botanic Garden of Berlin has long been regarded as one of the richest
in Europe. The fame of its extraordinary riches rested formerly on a
mere approximative estimate of its contents, and, as my old friend and
fellow-labourer Professor Kunth, has very correctly remarked,[NO] “it
was only by the completion of a systematic catalogue, based on the
most careful examination of the species, that an actual enumeration
could be undertaken. This enumeration gave somewhat more than 14,060
species; and when we deduct from these 375 cultivated ferns, there
remain 13,685 Phanerogamia, among which there are 1600 Composite, 1150
Leguminosæ, 428 Labiatæ, 370 Umbelliferæ, 460 Orchideæ, 60 Palms, and
600 Grasses and Cyperaceæ. If we compare with these numbers the number
of species given in recent works, as, for instance, Compositæ
(according to Decandolle and Walpers), at about 10,000, Leguminosæ
8070, Labiatæ (Bentham) 2190, Umbelliferæ 1620, Grasses 3544, and
Cyperaceæ 2000,[NP] we shall perceive that the Botanic Garden at
Berlin cultivates only ⅐, ⅛, and ⅑ of the very large families
(Compositæ, Leguminosæ, and Grasses), and as many as ⅕ and ¼ of the
already described species belonging to the small families (Labiatæ and
Umbelliferæ). If we estimate the number of all the different species
of Phanerogamia _simultaneously_ cultivated in all the botanical
gardens of Europe at 20,000, we shall find, as they appear to
constitute about the eighth part of those already described and
contained in herbariums, that the whole number of Phanerogamia must
amount to nearly 160,000. This estimate need not be regarded as too
high, since scarcely the hundredth part of many of the larger
families, as, for instance, Guttifereæ, Malpighiaceæ, Melastomeæ,
Myrtaceæ, and Rubiaceæ, belong to our gardens.” If we take the number
(26,660 species), given in Loudon’s “Hortus Britannicus,” as the
basis, we shall find, from the well-grounded series of inferences
drawn by Professor Kunth, and which I borrow from his manuscript
notice above referred to, that the estimate of 160,000 will increase
to 213,000 species; and even this is still very moderate, since
Heynhold, in his “Nomenclator botanicus hortensis” (1846), estimates
the species of Phanerogamia already cultivated at 35,600. On the
whole, therefore,—and the conclusion is, at first sight, sufficiently
striking,—the number of species of Phanerogamia at present known by
cultivation in gardens, by descriptions, and in herbariums, is almost
greater than that of known insects. According to the average estimates
of several of the most distinguished entomologists, whose opinion I
have been able to obtain, the number of insects at present described,
or contained in collections without being described, may be stated as
between 150,000 and 170,000 species. The rich collection at Berlin
contains fully 90,000, among which there are about 32,000 beetles.
Travellers have collected an immense quantity of plants in remote
regions, without bringing with them the insects living upon them, or
in the neighbourhood. If, however, we limit these numerical estimates
to a definite portion of the earth’s surface that has been the best
explored in regard to its plants and insects, as, for instance,
Europe, we find the ratio between the vital forms of Phanerogamic
plants and those of insects changed to such a degree, that while
Europe counts scarcely 7000 or 8000 Phanerogamia, more than three
times that number of European insects are at present known. According
to the interesting contributions of my friend Dohrn in Stettin, more
than 8700 insects have already been collected from the rich fauna of
the neighbourhood, and yet there are still many MicroLepidoptera
wanting; while the number of Phanerogamia found there scarcely exceeds
1000. The Insect-fauna of Great Britain is estimated at 11,600. Such a
preponderance of animal forms will appear less surprising when we
remember that several of the large classes of insects live only on
animal substances, whilst others subsist on agamic plants (Fungi), and
even on those which are subterranean. Bombyx Pini, the Pine Spider,
the most destructive of all forest-insects, is infested, according to
Ratzeburg, by no less than thirty-five parasitical Ichneumonidæ.
These considerations have led us to the proportion borne by the number
of species growing in gardens to the gross number of those already
described and preserved in herbariums; it now remains for us to
consider the proportion of the latter to the conjectural number of
species existing on the whole earth, or, in other words, to test their
minimum by the relative numbers of the different families—_i. e._ by
variable _multipla_. A test of this kind gives, however, such low
results for the _lower_ amount, as plainly to show that even in the
large families, which appear to have been the most strikingly enriched
in recent times by the researches of descriptive botanists, our
knowledge is still limited to a very small portion of the treasure
actually existing. The _Repertorium_ of Walpers which completes
Decandolle’s _Prodromus_ of 1825 to 1846, gives 8068 species of the
family of the Leguminosæ. We may assume the mean ratio to be ¹⁄₂₁;
since it is ⅒ in the tropical zone, ¹⁄₁₈ in the middle temperate zone,
and ¹⁄₃₃ in the cold northern zone. The _described_ Leguminosæ would
therefore only lead us to assume that there were 169,400 species of
Phanerogamia existing on the earth, whereas the Compositæ, as already
shewn, testify to the existence of more than 160,000 known
Phanerogamia, _i. e._ such as have been described or are contained in
herbariums. This discrepancy is instructive, and will be further
elucidated by the following analogous considerations.
The larger number of the Compositæ, of which Linnæus knew only 785
species, and which have now increased to 12,000, appear to belong to
the Old Continent. At least Decandolle described only 3590 American,
while he estimated the European, Asiatic, and African species at 5093.
This abundance of Compositæ in our vegetable systems is however
deceptive, and only apparently considerable; for the quotient of this
family (which within the tropical zone is ¹⁄₁₅, in the temperate zone
⅐, and in the frigid zone ¹⁄₁₃) shows that more species of Compositæ
than of Leguminosæ have hitherto eluded the diligent research of
travellers; for even when multiplied by 12 we only obtain the
improbably small number of 144,000 for the sum total of the
Phanerogamia! The families of the Grasses and of the Cyperaceæ give
still lower results, because a proportionally smaller number of
species have been described and collected. We need only cast a glance
at the map of South America, and remember that the vast extent of
country occupied by the grassy plains of Venezuela the Apure and the
Meta, as well as to the south of the woody region of the Amazon, in
Chaco, in Eastern Tucuman, and in the Pampas of Buenos Ayres and
Patagonia, has either been very imperfectly or not at all explored in
relation to botany. Northern and Central Asia present an almost
equally extensive territory occupied by steppes; but here a larger
proportion of dicotyledonous plants is intermixed with the Gramineæ.
If we had sufficient grounds for believing that one-half of all the
phanerogamic plants existing on the surface of the earth are known,
and if we estimate this number at only 160,000 or at 213,000 known
species; we must give to the family of grasses, whose general ratio
appears to be ¹⁄₁₂, in the former case at least 26,000, and in the
latter 35,000 different species, of which in the first case ⅛, and in
the second ⅒ are known.
The following considerations oppose the hypothesis that we are already
acquainted with half the Phanerogamia on the earth’s surface. Several
thousand species of Monocotyledons and Dicotyledons, and among them
lofty arborescent forms, have recently been discovered (I would remind
the reader of my own expedition) in districts of a very large extent,
which had already been explored by distinguished botanists. Yet that
portion of the great continents which has never been visited by
botanical observers far exceeds the extent of the parts even
superficially traversed. The greatest variety of phanerogamic
vegetation, _i. e._ the greatest number of species on an equal area,
is to be met with in the tropical or subtropical zones. It is
therefore the more important to bear in mind that we are almost wholly
unacquainted, north of the equator, in the New Continent, with the
floras of Oaxaca, Yucatan, Guatimala, Nicaragua, the Isthmus of
Panama, the Choco, Antioquia, and the Province de los Pastos; while
south of the equator, we are equally ignorant of the floras of the
boundless forest-region between the Ucayale, the Rio de la Madura, and
the Toncantin (three mighty tributaries of the Amazon), as well as of
those of Paraguay and the Province de las Missiones. In Africa, we
know nothing of the vegetation of the whole of the interior, between
15° north and 20° south lat.; and in Asia we are unacquainted with the
floras of the south and south-east of Arabia, where the highlands rise
to an elevation of 6400 feet; as also with the floras between the
Thian-schan, the Kuen-Lün, and the Himalaya; those of Western China;
and those of the great portion of the countries beyond the Ganges.
Still more unknown to botanists are the interior portions of Borneo
and New Guinea, and of some districts of Australia. Further to the
south the number of the species decreases in a most remarkable manner,
as Joseph Hooker has ably shown, from his own observation, in his
_Antarctic Flora_. The three islands which constitute New Zealand
extend from 34½° to 47¼° of latitude, and as they have besides
snow-crowned mountains more than 8850 feet in height, they must
exhibit considerable differences of climate. The most northern island
has been explored with tolerable accuracy from the time of Banks and
Solander’s voyage (with Capt. Cook), to the visits of Lesson, the
brothers Cunningham, and Colenso; and yet in more than seventy years,
the number of Phanerogamia with which we have become acquainted is
below 700.[NQ] This paucity of vegetable species corresponds with the
paucity of animal forms. Dr. Joseph Hooker has observed that “Iceland,
proverbially barren as it is, and upon which no tree, save a few
stunted birches, is to be found, possesses five times as many
flowering plants as Lord Auckland’s group and Campbell’s Islands
together, although these are situated at from 8° to 10° nearer the
equator in the southern hemisphere. The antarctic flora is at once
characterised by uniformity and great luxuriance of vegetation, which
is attributable to the influence exerted by an uninterruptedly cool
and humid climate. In Southern Chili, Patagonia, and Tierra del Fuego
(from 45° to 56° lat.) this uniformity is strikingly manifested on the
mountains and their declivities no less than in the plains. How great
is the difference of species when we compare the flora of the south of
France, in the same latitude as the Chonos Islands off the coast of
Chili, with the Scottish flora of Argyleshire, in the parallel of Cape
Horn. In the southern hemisphere the same types of vegetation pass
through many degrees of latitude. In the regions near the north pole
ten flowering plants have been collected on Walden Island (80½° north
lat.), while there is scarcely a solitary grass to be met with in the
South Shetland Islands, although situated 63° south latitude.”[NR]
These considerations on the distribution of plants prove that the
great mass of the still unobserved, uncollected, and undescribed
phanerogamia belong to the tropical zone, and to the contiguous
regions extending from twelve to fifteen degrees from it.
I have deemed it not unimportant to draw attention to the imperfect
state of our knowledge in this slightly cultivated department of
numerical botany, and to treat such questions in a more definite
manner than has hitherto been possible. In all conjectures regarding
relative numbers, we must first examine the practicability of
obtaining the _lowest limit_; as in the question, of which I have
treated elsewhere, regarding the ratio of the gold and silver coined
to the quantity of the precious metals existing in a wrought state; or
as in the question of how many stars, from the tenth to the twelfth
magnitude, are scattered over the heavens, and how many of the
smallest telescopic stars may be contained in the Milky Way?[NS] It is
an established fact, that if it were possible to ascertain completely
by observation the number of species of the large phanerogamic
families, we should at the same time obtain an approximate knowledge
of the sum-total of all the phanerogamia on the surface of the earth
(that is, the numbers included in every family). The more therefore we
are enabled, by the progressive exploration of unknown districts,
gradually to determine the number of species belonging to any one
great family, the higher will be the gradual rise of the lowest limit,
and the nearer we shall arrive at the solution of a great numerical
vital problem, since the forms, in accordance with still unexplained
laws of universal organism, reciprocally limit each other. But is the
number of the organisms a constant number? Do not new vegetable forms
spring from the ground after long intervals of time, whilst others
become more and more rare, and finally disappear? Geology confirms the
latter part of this question by means of the historical memorials of
ancient terrestrial life. “In the primitive world,” to use the
expression of the intellectual Link,[NT] “elements remote from each
other blend together in wondrous forms, indicating, as it were, a
higher degree of development and articulation in a future period of
the world.”
Footnote 84:
p. 222—“_Whether the height of the aërial ocean and its pressure have
always been the same_.”
The pressure of the atmosphere has a decided influence on the form and
life of plants. This life, owing to the fulness and abundance of the
leafy organs provided with interstitial openings, is principally
directed _outwards_. Plants mainly live in and through their surfaces,
and hence their dependence on the surrounding medium. Animals are more
dependant on _internal_ stimuli; they generate and maintain their own
temperature, deriving from muscular movements their electric currents,
and the chemical vital processes which arise from and re-act upon
those currents. A kind of cutaneous respiration constitutes an active
vital function of plants, and depends, so far as it is an evaporation,
inhalation, and exhalation of fluids, on atmospheric pressure. Hence
Alpine plants are more aromatic and hirsute than others, and more
amply provided with numerous exhalants.[NU] Zoonomic experiments teach
us, as I have shown in another work, that organs are more abundant and
more perfectly developed in proportion to the facility with which
their functional requirements are fulfilled. The disturbance
occasioned in the respiration of their external integuments, by
increased barometric pressure, renders it, as I have elsewhere shewn,
very difficult for Alpine plants to thrive in the plain.
Whether the aërial ocean surrounding the earth has always exerted the
same mean pressure is a question wholly undecided. We do not even know
for certain whether the mean barometric height has remained the same
during a hundred years at any one given spot. According to the
observations of Poleni and Toaldo, this pressure appeared variable.
Doubts were long entertained regarding the accuracy of these views,
but the more recent investigations of the astronomer Carlini render it
almost probable that in Milan the mean barometric pressure is on the
decrease. Perhaps the phenomenon is very local, and dependent on
periodic variations in descending currents of air.
Footnote 85:
p. 223—“_Palms_.”
It is remarkable, that of this majestic form of plants—the Palms—some
of which rise to more than twice the height of the Royal Palace at
Berlin, and which the Indian, Amarasinha, has very characteristically
called “kings among grasses,”—only fifteen species had been described
up to the time of the death of Linnæus. The Peruvian travellers, Ruiz
and Pavon, added only eight; whilst Bonpland and myself, traversing a
greater extent of country, from 12° south lat. to 21° north lat.,
described twenty new species, and distinguished as many more which we
named, without however being able to procure their blossoms in a
perfect state.[NV] At present (forty-four years after my return from
Mexico) more than 440 species of palms, from both continents, have
already been scientifically described, including the East Indian
species arranged by Griffith. The “Enumeratio Plantarum” of my friend
Kunth, which appeared in 1841, contains no fewer than 356 species.
The very few palms belonging, like our Coniferæ, Quercineæ, and
Betulineæ, to social plants, are the Mauritian Palm (_Mauritia
flexuosa_), and the two species of Chamærops, of which the Chamærops
humilis covers whole tracts of land at the estuary of the Ebro and in
Valencia, while the other, Chamærops Mocini, which we discovered on
the Mexican shore of the Pacific, is entirely without prickles. In the
same manner as there are some species of palms, including Cocos and
Chamærops, which are peculiar to sea-coasts, so also is there a
certain group of Alpine palms belonging to the region of the tropics,
which, if I mistake not, was wholly unknown before my South American
journey. Almost all these species of the palm family grow in plains
and in a mean temperature of 81°.5 and 86° Fahr., seldom advancing
higher up the sides of the Andes than to 1900 feet. The beautiful wax
palm (_Ceroxylon andicola_), the Palmetto of Azufral at the Pass of
Quindiu, (_Oreodoxa frigida_), and the reed-like Kunthia montana
(_Caña de la Vibora_) of Pasto, all flourish at elevations varying
from 6400 to 9600 feet above the level of the sea, where the
thermometer frequently sinks in the night to 42°.8 and 45°.5 Fahr.,
and the mean temperature is scarcely 57° Fahr. These Alpine palms are
interspersed with nut-trees, yew-leaved species of Podocarpus, and
oaks, (_Quercus granatensis_). I have determined, by accurate
barometric measurements, the upper and lower limits of the wax palm.
We began to observe it first on the eastern declivity of the
Cordilleras of Quindiu, at an elevation of 7929 feet, from whence it
ascended to the Garita del Paramo, and Los Volcancitos, as high as
about 9700 feet. The distinguished botanist, Don José Caldas, who was
long our companion in the mountains of New Granada, and who fell a
victim to Spanish party hatred, found, many years after my departure
from the country, three species of palms in the Paramo de Guanacos, in
the immediate vicinity of the limit of perpetual snow, and therefore,
probably at an elevation of nearly 14,000 feet.[NW] Even beyond the
tropical region (in lat. 28°), Chamærops Martiana[NX] rises on the
advanced spurs of the Himalaya range to a height of 5000 feet.
When we consider the extreme geographical and, consequently, also the
climatic limits of palms at spots which are but little elevated above
the level of the sea, we find that some forms (the Date Palm,
_Chamærops humilis_, _Ch. palmetto_, and _Areca sapida_ of New
Zealand,) advance far within the temperate zone of both hemispheres,
to districts where the mean annual temperature scarcely reaches from
57° to 60° Fahr. If we form a progressive scale of cultivated plants
in accordance with the different degrees of heat they require, and
begin with the maximum, we have Cacao, Indigo, Bananas, Coffee,
Cotton, Date Palms, Orange and Lemon trees, Olives, Spanish Chesnuts,
and Vines. In Europe, Date Palms, together with Chamærops humilis,
grow in the parallels of 43½° and 44°, as, for instance, on the
Genoese Rivera del Ponente, near Bordighera, between Monaco and San
Stefano, where there is a palm grove, numbering more than 4000 trees;
also in Dalmatia, near Spalatro. It is remarkable that the Chamærops
humilis is of frequent occurrence in the neighbourhood of Nice and in
Sardinia, whilst it is not found in the Island of Corsica, lying
between the two. In the New Continent, the Chamærops palmetto, which
is sometimes more than 40 feet high, does not advance further north
than 34°; a circumstance that may be explained by the inflection of
the isothermal lines. In the southern hemisphere, Robert Brown[NY]
found that palms, of which there are only very few (six or seven)
species, advance as far as 34° in New Holland; while Sir Joseph Banks
saw an Areca, in New Zealand, as far as 38°. Africa, which, contrary
to the ancient and still extensively diffused opinion, is poor in
species of palms, exhibits only one palm (_Hyphæne coriacea_) which
advances south of the equator, only as far as Port Natal, in 30° lat.
The continent of South America presents almost the same limits. East
of the chain of the Andes, in the Pampas of Buenos Ayres, and in the
Cis-Plata province, palms extend, according to Auguste de
St.-Hilaire,[NZ] as far as 34° and 35°. The Coco de Chile, (our Jubæa
spectabilis?), the only species of palm indigenous in Chili, advances
on the western side of the chain of the Andes, according to Claude
Gay,[OA] to an equal latitude, viz., to the Rio Maule.
I will here subjoin the aphoristic observations which, in March, 1801,
I noted down while on board ship, at the moment we were leaving the
palm region surrounding the mouth of the Rio Sinu, west of Darien, and
were setting sail for Carthagena de Indias.
“In the space of two years, we have seen as many as 27 different
species of palms in South America. How many then must have been
observed by Commerson, Thunberg, Banks, Solander, the two Forsters,
Adanson, and Sonnerat, on their extensive travels! Yet, at the moment
I am writing, our vegetable systems recognise scarcely more than from
fourteen to eighteen methodically described species of palms. The
difficulties of reaching and procuring the blossoms of palms are, in
fact, greater than can well be conceived; and, in our own case, we
were made peculiarly sensible of this in consequence of our having
directed our attention especially to palms, grasses, cyperaceæ,
juncaceæ, cryptogamia, and numerous other subjects hitherto much
neglected. Most of the palms flower only once a year, and this period
near the equator is generally about the months of January and
February. How few travellers are likely to be in the region of palms
precisely during this season! The period of blossoming of particular
trees is often limited to a few days, and the traveller commonly
finds, on his arrival in the region of palms, that the blossoms have
passed away, and that the trees present only fructified ovaries and no
male flowers. In an area of 32,000 square miles, there are often not
more than three or four species of palms to be found. Who can
possibly, during the brief period of flowering, simultaneously visit
the various palm regions near the Missions on the Rio Caroni, in the
Morichales at the mouth of the Orinoco, in the valley of Caura and
Erevato, on the banks of the Atabapo and the Rio Negro, and on the
declivity of the Duida? There is, moreover, great difficulty when the
trees grow in thick woods or on swampy shores (as at the Temi and
Tuamini), in reaching the blossoms, which are often suspended from
stems formidably armed with huge thorns, and rising to a height of
between 60 and 70 feet. They who contemplate distant travels from
Europe for the purpose of investigating subjects of natural history,
picture to themselves visions of efficient shears and curved knives
attached to poles, ready for securing anything that comes in their
way; and of boys who, obedient to their mandates, are prepared, with a
cord attached to their feet, to climb the loftiest trees!
Unfortunately, scarcely any of these visions are ever realised; while
the flowers are almost unattainable, owing to the great height at
which they grow. In the missionary settlements of the river net-work
of Guiana, the stranger finds himself amongst Indians, who, rendered
rich and independent by their apathy, their poverty, and their
barbarism, cannot be induced either by money or presents to deviate
three steps from the regular path, supposing one to exist. This
stubborn indifference of the natives provokes the European so much the
more, from his being continually a witness of the inconceivable
agility with which they will climb any height when prompted by their
own inclination, as, for instance, in the pursuit of a parrot, an
iguana, or a monkey, which, wounded by their arrows, saves itself from
falling by its prehensile tail. In the month of January the stems of
the _Palma Real_, our _Oreodoxa Regia_, were covered with snow-white
blossoms, in all the most frequented thoroughfares of the Havannah,
and in the immediate vicinity of the city; but, although we offered,
for several days running, a couple of piastres for a single spadix of
the hermaphrodite blossoms to every negro boy we met in the streets of
Regia and Guanavacoa, it was in vain, for, in the tropics, no free man
will ever undertake any labour attended by fatigue unless he is
compelled to do so by imperative necessity! The botanists and painters
of the Royal Spanish Commission of Natural History under Count Don
Jaruco y Mopox (Estevez, Boldo, Guio, Echeveria), confessed to us
that, for several years, they had been unable to examine these
blossoms, owing to the absolute impossibility of obtaining them.
“After this statement of the difficulties attending their acquisition,
the fact of our being only able, in the course of two years,
systematically to describe twelve species of palms, although we had
discovered twenty species, may be understood; but I confess it would
hardly have been credible to me before I left Europe. How interesting
a work might be written on palms by a traveller, who could exclusively
devote himself to the delineation, in their natural size, of the
spathe, spadix, inflorescence and fruits!” (Thus I wrote many years
before the Brazilian travels of Martius and Spix, and the appearance
of the admirable work on Palms by the former.)
“There is much sameness in the form of the leaves, which are either
feathery (pinnata), or fan-like (palmo-digitata); the leaf-stalk
(petiolus) is either without thorns or is sharply serrated
(_serrato-spinosus_). The leaf-form of _Caryota urens_ and _Martinezia
caryotifolia_, which we saw on the banks of the Orinoco and the
Atabapo, and subsequently in the Andes, at the pass of Quindiu, as
high as 3200 feet above the level of the sea, is almost as peculiar
among palms as is the leaf-form of the Gingko among trees. The habitus
and physiognomy of palms are expressive of a grandeur of character
which it is difficult to describe in words. The stem (_caudex_) is
simple, and very rarely divided into branches after the manner of the
Dracæna, as in Cucifera thebaica (the Doom Palm), and in Hyphæne
coriacea. It is sometimes disproportionately thick, as in Corozo del
Sinu, our Alfonsia oleifera; of a reed-like feebleness, as in Piritu,
(_Kunthia montana_), and the Mexican Corypha nana; of a somewhat
fork-like and protuberant form towards the lower part, as in Cocos;
sometimes smooth and sometimes scaly, as in the Palma de Covijaó de
Sombrero, in the Llanos; or, lastly, prickly, as in Corozo de Cumana
and Macanilla de Caripe, having the thorns very regularly arranged in
concentric rings.
“Characteristic differences also manifest themselves in the roots,
which, in some cases, project about a foot or a foot and a half from
the ground, raising the stem on a scaffolding, as it were, or coiled
round it in a padded-like roll. I have seen viverras and even very
small monkeys pass under the scaffolding formed by the roots of the
Caryota. Occasionally the stem is swollen only in the middle, being
smaller above and below, as in the Palma Real of the island of Cuba.
The green of the leaves is either dark and shining, as in Mauritia
Cocos, or of a silvery white on the under side, as in the slender
fan-palm, _Corypha Miraguama_, which we saw in the harbour of Trinidad
de Cuba. Sometimes the middle of the fan-like leaf is adorned with
concentric yellow and blue stripes, in the manner of a peacock’s tail,
as in the prickly Mauritia, which Bonpland discovered on the Rio
Atabapo.
“The direction of the leaves is a no less important characteristic
than their form and colour. The leaflets (foliola) are either ranged
in a comb-like manner close to one another, with a stiff parenchyma
(as in _Cocos Phœnix_), to which they owe the beautiful reflections of
solar light that play over the surface of the leaves, which shine with
a brilliant verdure in _Cocos_, and with a fainter and ashy-coloured
hue in the date-palm; or sometimes the foliage assumes a reed-like
appearance, having a thinner and more flexible texture, and being
curled near the extremity (as in _Jagua_, _Palma Real del Sinu_,
_Palma Real de Cuba_, and _Piritu del Orinoco_). This direction of the
leaves, together with the lofty stem, gives to the palms their
character of high majesty. It is a characteristic of the
physiognomical beauty of the palm that its leaves are directed
aspiringly upwards throughout the whole period of its duration, (and
not only in the youth of the tree, as is the case with the Date-Palm,
which is the only one introduced into Europe.) The more acute the
angle made by the leaves with the upper part of the stem (that is, the
nearer they approach the perpendicular,) the grander and nobler is the
form of the tree. How different is the aspect of the pendent leaves of
the _Palma de Covija del Orinoco y de los Llanos de Calabozo_ (Corypha
tectorum), from the more horizontal leaves of the Date and Cocoa-nut
palms, and the lofty heavenward-pointing branches of the _Jagua_, the
_Cucurito_, and _Pirijao_.
“Nature seems to have accumulated all the beauties of form in the
Jagua palm, which, intermingled with the Cucurito or Vadgihai, whose
stem rises to a height of 80 or even more than 100 feet, crowns the
granite rocks at the cataracts of Atures and Maypures, and which we
also occasionally saw on the lonely banks of the Cassiquiare. Their
smooth and slender stems rise to a height of from 64 to 75 feet,
projecting like a colonnade above the dense mass of the surrounding
foliage. These aërial summits present a marked and beautiful contrast
with the thickly-leaved species of _Ceiba_, and with the forest of
_Laurineæ_, _Calophyllum_, and the different species of _Amyris_ which
surround them. Their leaves, which seldom exceed seven or eight in
number, incline vertically upwards to a height of 16 or 17 feet, and
are curled at the extremities in a kind of feathery tuft. The
parenchyma of the leaf is of a thin grass-like texture, causing the
leaflets to wave with graceful lightness on the gently oscillating
leaf-stalk. The floral buds burst forth, in all species of palms, from
the stem immediately beneath the leaves; and the mode in which this
takers place modifies their physiognomical character. Thus in some, as
in _Corozo del Sinu_, the sheath is perfectly erect, and the fruit
rises like a thyrsus, resembling the fruits of the Bromelia. In the
greater number, the sheaths, which in some species are smooth, and in
others very prickly and rough, incline downwards. In some, again, the
male blossoms are of a dazzling white, and it may then be seen shining
from a great distance; but in most species of palms they are yellow,
closely compressed, and of an almost faded appearance, even when they
first burst from the spathe.
“In palms with feathery leaves the leaf-stalks either burst from the
dry, rough, ligneous portion of the stem (as in _Cocos_, _Phœnix_,
_Palma Real del Sinu_), or there rises in the rough part of the stem a
grass-green, smooth, and thinner shaft, like one column above another,
from which the leaf-stalk springs, as in _Palma Real de la Havana_,
_Oreodoxa regia_, which excited the admiration of Columbus. In the
fan-palms (_foliis palmatis_), the leafy crown often rests on a layer
of dry leaves, which imparts to the tree a character of melancholy
solemnity and grandeur (as in _Moriche_, _Palma de sombrero de la
Havana_). In some umbrella-palms, the crown consists of a very few
scattered leaves, raised on slender stalks (as in _Miraguama_).
“The form and colour of the fruit also present more variety than is
generally supposed to be the case in Europe. _Mauritia flexuosa_ has
egg-shaped fruits, whose smooth, brown, and scaly surface gives them
the appearance of young pine cones. How great is the difference
between the large triangular cocoa-nut, the berry of the date, and the
small stone-fruit of the Corozo! But of all the fruits of the palm,
none can be compared for beauty with those of the Pirijao (_Pihiguao_)
of San Fernando de Atabapo and of San Balthasar. They are oval, and of
a golden colour (one-half being of a purplish red); are mealy, without
seed, two or three inches in thickness, and hang in clusters like
grapes from the summits of their majestic palm-trunks.” I have already
spoken in the earlier part of this work of these beautiful fruits, of
which there are seventy or eighty clustered together in one bunch, and
which can be prepared in a variety of ways like bananas and potatoes.
The spathe enclosing the blossom bursts suddenly open in some species
of palms, with an audible report. Richard Schomburgk has like myself
observed this phenomenon[OB] in the flowering of the Oreodoxa
oleracea. This first opening of the blossoms of the palm accompanied
with noise, reminds us of Pindar’s Dithyrambus on Spring, and of the
moment when in the Argive Nemæa, “the first opening shoot of the
date-palm announces the coming of balmy spring.”[OC]
Palms, bananas, and arborescent ferns constitute three forms of
especial beauty peculiar to every portion of the tropical zone;
wherever heat and moisture co-operate, vegetation is most exuberant
and vegetable forms present the greatest diversity. Hence South
America is the most beautiful portion of the palm world. In Asia the
palm form is rare, in consequence perhaps of a considerable part of
the Indian continent beneath the equator having been destroyed and
covered by the ocean in some earlier revolution of our planet. We know
scarcely anything of the African palms between the Bay of Benin and
the coast of Ajan; and we are, generally speaking, as already
observed, acquainted with only a very small number of African
palm-forms.
Palms, next to Coniferæ, and some species of Eucalyptus belonging to
the family of the Myrtaceæ, afford examples of the loftiest growth.
Stems of the Cabbage-palm (_Areca oleracea_) have been seen from 160
to 170 feet in height.[OD] The Wax-palm, our Ceroxylon andicola, which
we discovered in the Montaña de Quindiu on the side of the Andes,
between Ibague and Carthago, attains the enormous height of 180 to 190
feet. I was able to make an accurate measurement of the trunks of some
of these trees, which had been felled in the woods. Next to the
Wax-palm, the Oreodoxa Sancona, which we found in flower in the valley
of Cauca, and which affords a very hard and admirable wood for
building, appeared to me to be the highest of all American palms. The
fact, that notwithstanding the enormous mass of fruit yielded by some
single palms, the number of individuals of each species growing wild
is not very considerable, can only be explained by the frequent
abortive development of the fruit, and by the voracity of the enemies
by whom they are assailed from all classes of animals. In the basin of
the Orinoco, however, whole tribes find the means of subsistence for
many months together in the fruit of the palm. “In palmetis, Pihiguao
consitis, singuli trunci quotannis fere 400 fructus ferunt pomiformes,
tritumque est verbum inter Fratres S. Francisci, ad ripas Orinoci et
Guainiæ degentes, mire pinguescere Indorum corpora, quoties uberem
Palmæ fructum fundant.”[OE]
Footnote 86:
p. 224—“_From the earliest infancy of human civilization_.”
We find, as far as history and tradition extend, that the Banana has
constantly been cultivated in all continents within the tropical zone.
The fact of African slaves having, in the course of centuries, brought
some varieties of the Banana fruit to America is as certain as that of
the cultivation of this vegetable product by the natives of America
prior to its discovery by Columbus. The Guaikeri Indians in Cumana
assured us that on the coast of Paria, near the Golfo Triste, the
Banana will occasionally produce germinating seeds, if the fruit be
suffered to ripen on the stem. It is from this cause, that wild
Bananas are occasionally found in the recesses of the forests, in
consequence of the ripe seeds being scattered abroad by birds. At
Bordones also, near Cumana, perfectly formed and matured seeds have
been occasionally found in the fruit of the Banana.[OF]
I have already remarked, in another work,[OG] that Onesicritus and
other companions of the great Macedonian, make no mention of high
arborescent ferns, although they speak of the fan-leaved umbrella
palms and of the tender evergreen verdure of the banana-plantations.
Among the Sanscrit names given by Amarasinha for the Banana (the
_Musa_ of botanists) we find _bhanu-phala_ (sun-fruit),
_varana-buscha_, and _moko_. Phala signifies fruit generally. Lassen
explains Pliny’s words (xii. 6), “Arbori nomen palæ, pomo arienæ,” to
this effect, that “The Roman mistook the word _pala_, fruit, for the
name of the tree, whilst _varana_, changed in the mouth of a Greek to
_ouarana_, was transformed into _ariena_. The Arabic _mauza_, our
Musa, may have been formed from _moko_. The Bhanu fruit seems to
approach to Banana fruit.”[OH]
Footnote 87:
p. 224—“_Form of the Malvaceæ_.”
Larger forms of the Mallow appear, as soon as we have crossed the
Alps; _Lavatera arborea_, near Nice and in Dalmatia; and _L. olbia_,
in Liguria. The dimensions of the Baobab (monkey bread-tree) have
already been given. (See pp. 270–272.) With the form of the Malvaceæ
are associated the botanically allied families of the Byttneriaceæ,
(_Sterculia_, _Hermannia_, and the blossoms of the large-leaved
_Theobroma Cacao_, whose flowers break forth from the bark of the
trunk as well as from the roots); the Bombaceæ (_Adansonia_,
_Helicteres_, and _Cheirostemon_); and, lastly, the Tiliaceæ
(_Sparmannia Africana_). Our _Cavanillesia plantanifolia_ of Turbaco,
near Carthagena in South America, and the celebrated Ochroma-like
Hand-tree, the _Macpalxochiquahuitl_ of the Mexicans, (from Macpalli,
the flat of the hand,) _Arbol de las manitas_ of the Spaniards, our
_Cheirostemon platanoides_, are splendid representatives of the mallow
form. In the last named, the anthers are connected together in such a
manner as to resemble a hand or claw rising from the beautiful
purplish-red blossoms. There is in all the Mexican free states only
one individual remaining, one single primæval stem of this wonderful
genus. It is supposed not to be indigenous, but to have been planted
by a king of Toluca, about five hundred years ago. I found that the
spot where the Arbol de las Manitas stands is 8825 feet above the
level of the sea. Why is there only one tree of the kind? Whence did
the kings of Toluca obtain the young tree or the seed? It is equally
enigmatical, that Montezuma should not have possessed one of these
trees in his botanical gardens of Huaxtepec, Chapoltepec, and
Iztapalapan, which were used as late as by Philip the Second’s
physician, Hernandez, and of which gardens traces still remain; and it
appears no less striking that the Hand-tree should not have found a
place among the drawings of subjects connected with natural history,
which Nezahual Coyotl, king of Tezcuco, caused to be made, half a
century before the arrival of the Spaniards. It is asserted that the
Hand-tree grows wild in the forests of Guatimala.[OI] We found two
Malvaceæ, _Sida Phyllanthos_ (Cavan.), and _Sida Pichinchensis_,
rising in the equatorial region to the great height of 13,430, and
15,066 feet on the mountain of Antisana and at the volcano of Rucu
Pichincha.[OJ] The _Saxifraga Boussingaultii_ rises from 600 to
upwards of 700 feet higher, on the declivity of Chimborazo.
Footnote 88:
p. 225—“_Form of the Mimosæ_.”
The delicate and feathery foliage of the Mimosæ, Acaciæ, Schrankiæ,
and Desmanthus, may be regarded as peculiarly characteristic of
tropical vegetation; although some representatives of this form may
also be found without the tropics. In the Old Continent of the
northern hemisphere, and indeed in Asia, I can instance only one low
shrub, described by Marshal von Bieberstein as _Acacia Stephaniana_,
but which, according to Kunth’s more recent investigations, is a
species of the genus _Prosopis_. This social plant covers the arid
plains of the province of Schirvan on the Kur (Cyrus), near New
Schamach, as far as the ancient Araxes. Olivier found it also in the
neighbourhood of Bagdad. It is the _Acacia foliis bipinnatis_
mentioned by Buxbaum, and which extends towards the north as far as
42° lat.[OK] In Africa the _Acacia gummifera_ (Willd.), extends to
Mogador, and therefore as far as 32° north lat.
In the New Continent, _Acacia glandulosa_ (Michaux), and _A.
brachyloba_ (Willd.), adorn the banks of the Mississippi and
Tennessee, and the Savannahs of the Illinois. The _Schrankia uncinata_
was found by Michaux to penetrate from Florida northwards to Virginia
(therefore as far as 37° north lat.). _Gleditschia triacanthos_ is met
with, according to Barton, to the east of the Alleghany mountains, as
far as 38° north lat., and west of the same range even to 41° north
lat. The extreme northern limit of _Gleditschia monosperma_ is two
degrees further southward. Such are the boundaries of the Mimosa form
in the northern hemisphere, while in the southern hemisphere, beyond
the tropic of Capricorn, simple-leaved Acaciæ are found as far as Van
Dieman’s Land; the Acacia cavenia described by Claude Gay being even
found in Chili between 30° and 37° south lat.[OL] Chili has no true
Mimosa, but three species of Acacia; and even in the north of Chili
the Acacia cavenia grows only to a height of 12 or 13 feet, whilst in
the south, as it approaches the sea-coast, it scarcely rises a foot
above the ground. The most sensitive of the Mimosas which we saw in
the northern portion of South America, are (next to the Mimosa
pudica,) _M. dormiens_, _M. somnians_, and _M. somniculosa_. The
irritability of the African sensitive plant was already noticed by
Theophrastus (iv. 3), and by Pliny (xiii. 10); but I find the first
description of the South American sensitive plants (Dormideras) in
Herrera (Decad. ii. lib. iii. cap. 4). The plant first attracted the
attention of the Spaniards, in 1518, in the Savannahs on the isthmus
round Nombre de Dios (“parece como cosa sensible”), and it was
pretended that the leaves (“de echura de una pluma de pajaros,”) only
contracted together when they were touched with the finger, and not
when brought in contact with a piece of wood. In the small swamps
which surround the town of Mompox on the Magdalena River, we
discovered a very beautiful aquatic Mimosa (_Desmanthus lacustris_), a
representation of which is given in our “Plantes équinoxiales” (t. i.
p. 55, pl. 16). In the chain of the Andes of Caxamarca we found two
Alpine Mimosas (Mimosa montana and Acacia revoluta) growing at
elevations of from 9000 to nearly 9600 feet above the level of the
sea.
As yet no true Mimosa, (in the meaning of the word as established by
Willdenow,) nor even any Inga, has been found in the temperate zone.
Amongst all the Acacias the Oriental _Acacia Julibrissin_, which
Forskäl has confounded with _Mimosa arborea_, endures the greatest
degree of cold. In the Botanical Garden of Padua there is a high stem
of considerable thickness growing in the open air, although the mean
temperature of Padua is below 56° Fahrenheit.
Footnote 89:
p. 225.—“_Heaths_.”
We do not, in these physiognomical considerations, by any means
comprehend, under the name of Heaths, the whole natural family of the
Ericaceæ, which, on account of the similarity and analogy in the
flowering parts of the plant, include Rhododendrum, Befaria,
Gaultheria, and Escallonia; we limit ourselves to the very accordant
and characteristic form of the species of Erica, including Calluna
(_Erica vulgaris_, L.).
“Whilst in Europe Erica carnea, E. tetralix, E. cinerea, and Calluna
vulgaris, cover large tracts of country, extending from the plains of
Germany, and from France and England, to the extremity of Norway;
Southern Africa presents the most varied assortment of species. One
single species, Erica umbellata, which is indigenous in the southern
hemisphere, at the Cape of Good Hope, is again found in Northern
Africa, Spain, and Portugal. Erica vagans and E. arborea also belong
to the opposite coasts of the Mediterranean. The former is met with in
Northern Africa, in the neighbourhood of Marseilles, in Sicily and
Dalmatia, and even in England; the second in Spain, Istria, Italy, and
the Canaries.”[OM] The common heath, _Calluna vulgaris_ (Salisbury),
which is a social plant, covers large tracts from the mouth of the
Scheldt to the western declivity of the Ural. Beyond the Ural both
Oaks and Heaths disappear. Both are wanting in the whole of Northern
Asia, and in all Siberia, as far as the Pacific. Gmelin[ON] and
Pallas[OO] have expressed their astonishment at this disappearance of
Calluna vulgaris; which, on the eastern declivity of the Ural chain is
even more decided and more sudden than one might be led to conclude,
from the words of the last-named great naturalist. Pallas merely says,
“ultra Uralense jugum sensim deficit, vix in Isetensibus campis
rarissime apparet, et ulteriori Sibiriæ plane deest.” Chamisso, Adolph
Erman, and Heinrich Kittlitz collected Andromedas but no Calluna in
Kamtschatka and on the north-west coast of America. The accurate
knowledge which we at present possess of the mean temperature of
different portions of Northern Asia, as well as of the distribution of
annual heat throughout the different seasons, in no way explains the
non-advance of the Heath to the east of the Ural. Dr. Joseph Hooker
has treated with much ingenuity, in a note to his “Flora Antarctica,”
of the two contrasting phenomena of the distribution of plants,
“uniformity of surface accompanied by a similarity of vegetation”, and
again, “instances of a sudden change in the vegetation, unaccompanied
with any diversity of geological and other feature.”[OP] Is there an
Erica in Central Asia? That which Saunders, in Turner’s “Travels to
Thibet,”[OQ] has described in the highlands of Nepaul, besides other
European plants (Vaccinium Myrtillus, and V. oxycoccus), as Erica
vulgaris, is, according to the opinion communicated to me by Robert
Brown, probably the Andromeda fastigiata of Wallich. The absence of
Calluna vulgaris and of all species of Erica, throughout the whole of
the continental part of America is an equally striking fact, since
Calluna is met with in the Azores and in Iceland. It has not hitherto
been found in Greenland, but it was discovered some years ago in
Newfoundland. The natural family of the Ericaceæ is also almost
entirely wanting in Australia, where its place is supplied by the
Epacrideæ. Linnæus described only 102 species of the genus Erica, but,
according to Klotzsch’s observations, this genus comprises 440 true
species, after the varieties have been carefully excluded.
Footnote 90:
p. 226—“_The Cactus form_.”
When the natural family of the Opuntiaceæ is separated from the
Grossulariaceæ (species _Ribes_), and is confined within the limits
indicated by Kunth,[OR] we may regard the whole as exclusively
American. I am not ignorant, that Roxburgh, in the _Flora indica_
(inedita), mentions two species of Cactus which he regards as peculiar
to the south-east of Asia, viz., Cactus indicus, and C. chinensis.
Both are widely diffused, originally wild or having become so, and
different from Cactus opuntia and C. Coccinellifer; but it is
remarkable that this Indian plant should have no ancient Sanscrit
name. The so-called Chinese Cactus has been introduced by cultivation
into the island of St. Helena. Modern investigations, prosecuted at a
period when a more general interest has been awakened in relation to
the original distribution of plants, will unquestionably remove the
doubts that have frequently been advanced against the existence of
Asiatic Opuntiaceæ. We see, in a similar manner, certain vital forms
appear separately in the animal world. How long did the Tapir continue
to be regarded as a characteristic form of the New Continent! And yet
the American Tapir is, as it were, repeated in that of Malacca
(_Tapirus indicus_, Cuv.).
Although the Cactus form belongs, properly speaking, to the tropical
regions, there are some species in the New Continent, that are
indigenous to the temperate zone on the Missouri and in Louisiana; as,
for instance, Cactus missuriensis and C. vivipara. Back, in his
northern expedition, saw with astonishment, the banks of the Rainy
Lake in lat. 48° 40′ (long. 92° 53′) entirely covered with C. Opuntia.
South of the equator the Cactus does not advance further than Rio
Itata (lat. 36°) and Rio Biobio (lat. 37¼°) In the part of the chain
of the Andes lying within the tropics, I have found species of Cactus
(_C. sepium_, _C. chlorocarpus_, _C. bonplandii_) on elevated plains
from 9000 to upwards of 10,600 feet above the level of the sea; but in
Chili, in the temperate zone, a far more strongly marked Alpine
character is exhibited by Opuntia Ovallei, whose upper and lower
limits have been accurately determined through barometric measurements
by the learned botanist, Claude Gay. The yellow-flowering Opuntia
Ovallei, which has a creeping stem, does not descend below 6746 feet,
advancing as high as the line of perpetual snow; and even above it,
wherever a few masses of rock remain uncovered. These little plants
have been gathered at spots lying at an elevation of 13,663 feet above
the level of the sea.[OS] Some species of Echinocactus are also true
alpine plants in Chili. A counterpart to the much admired fine-haired
Cactus senilis is presented by the thick-wooled Cereus lanatus, called
by the natives _Piscol_, which has a fine red fruit. We found it near
Guancabamba, in Peru, on our journey to the Amazon river. The
dimensions of the Cactaceæ (a group on which the Prince of Salm-Dyck
was the first to throw considerable light) present the most striking
contrasts. Echinocactus Wislizeni, which has a circumference of seven
feet and a half, with a height of four feet and a quarter, is only
third in size, being surpassed by E. ingens, (Zucc.) and E.
platyceras. (Lem.)[OT] The Echinocactus Stainesii attains a diameter
of from two feet to two and a-half; E. visnago, belonging to Mexico,
has a diameter of upwards of three feet, with a height of more than
four feet, and weighs as much as from 700 to 2000 lbs.; while the
Cactus nanus, which we collected near Sondorillo, in the province of
Jaen, is so small and so loosely rooted in the sand, that it gets
between the toes of dogs. The Melocactuses, which are full of juice
even in the driest season, as the Ravenala of Madagascar (wood-leaf in
the language of the country from _rave_, _raven_, a leaf, and _ala_,
the Javanese _halas_, a wood), are vegetable springs, which the wild
horses and mules open by stamping with their hoofs—a process in which
they frequently injure themselves.[OU] Cactus Opuntia has spread
during the last quarter of a century in a remarkable manner through
Northern Africa, Syria, Greece, and the whole of Southern Europe;
penetrating from the coasts of Africa far into the interior, where it
associates with the native plants.
After being accustomed to see Cactuses only in our hothouses, we were
astonished at the density of the woody fibres in old cactus stems. The
Indians are aware that cactus wood is indestructible, and admirably
adapted for oars and the thresholds of doors. There is hardly any
physiognomical character of exotic vegetation that produces a more
singular and ineffaceable impression on the mind of the traveller,
than an arid plain densely covered with columnar or candelabra-like
stems of cactuses, similar to those near Cumana, New Barcelona, Coro,
and in the province of Jaen de Bracamoros.
Footnote 91:
p. 226—“_Orchideæ_.”
The almost animal-like form occasionally observed in blossoms of the
Orchideæ is most strongly marked in Anguloa grandiflora, celebrated in
South America as the Torito; in the Mosquito (our Restrepia
antennifera); in the Flor del Espiritu Santo (likewise an Anguloa,
according to _Floræ Peruvianæ Prodrom._ p. 118, tab. 26); in the
ant-like flower of Chiloglottis cornuta;[OV] in the Mexican Bletia
speciosa; and in the whole host of our remarkable European species of
Ophrys: _O. muscifera_, _O. apifera_, _O. aranifera_, _O. arachnites_,
_&c._ The taste for these splendidly flowering plants has so much
increased, that the number of species cultivated by Messrs. Loddige,
which, in 1813, was only 115, was upwards of 1650 in 1843, and in
1848, the number was estimated at no fewer than 2360. What a treasure
of sumptuously flowering and unknown Orchideæ may be inclosed in the
interior of Africa wherever there is an abundant supply of water!
Lindley, in his beautiful work, _On the Genera and Species of
Orchideous Plants_, 1840, counted exactly 1980 species; whilst
Klotzsch at the close of the year 1848 counted 3545.
Whilst the temperate and cold zone possess only terrestrial Orchideæ,
growing close to the ground, both forms, the terrestrial, as well as
the parasitical, growing on the trunks of trees, are indigenous in the
beautiful regions of the tropics. To the former class belong the
tropical genera Neottia, Cranichis, and most Habenarias. But we have
found both these forms as alpine plants on the declivity of the Andes
of New Granada and Quito, viz., the parasitical (_Epidendreæ_)
Masdevallia uniflora (at an elevation of 10,231 feet), Cyrtochilum
flexuosum (at 10,103 feet), and Dendrobium aggregatum (at 9485 feet);
and the terrestrial forms of Altensteinia paleacea, near Lloa
Chiquito, at the foot of the volcano of Pichincha. Claude Gay is of
opinion that the Orchideæ supposed to have been found growing on trees
in the Island of Juan Fernandez and even at Chiloe, were probably only
parasitical Pourretiæ, which advance as far south at least as 40°. In
New Zealand, the tropical form of Orchideæ, hanging from trees, is
still to be seen as far south as 45°. But the Orchideæ of Auckland and
Campbell Islands (Chiloglottis, Thelymitra, and Acianthus), grow on
level ground in moss. In the animal world there is at least one
tropical form that penetrates further south. The Island of Macquarie
(lat. 54° 39′) has an indigenous parrot, which lives therefore in a
region nearer to the south pole than Danzig is to the north pole.[OW]
Footnote 92:
p. 226—“_Form of the Casuarinæ_.”
Acacias, in which the place of the leaves is supplied by phyllodia,
Myrtaceæ (Eucalyptus, Metrosideros, Melaleuca, Leptospermum), and
Casuarinæ, constitute the sole characteristics of the vegetable world
of Australia (New Holland) and Tasmania (Van Diemen’s Land). Casuarinæ
with their leafless, thin, thread-like, articulated branches, and
their joints furnished with membranous, toothed spathes, have been
compared by travellers,[OX] according to differences of species,
either with arborescent Equisetaceæ (Horsetails) or with our Scotch
firs. I have been much struck with the singular appearance of
leaflessness presented by the small thickets of Colletia and Ephedra
in South America, near the coast of Peru. Casuarina quadrivalvis
penetrates, according to Labillardière, as far south as 43° in
Tasmania. The mournful form of the Casuarina is not unknown in the
East Indies and even on the eastern coast of Africa.
Footnote 93:
p. 227—“_Acicular-leaved trees_.”
The family of the Coniferæ (including the genera of Dammara, Ephedra,
and Gnetum of Java and New Guinea, which are essentially allied to it,
though distinctly separated by the form of the leaf and the whole
conformation), plays so important a part in consequence of the number
of individuals in each species, and by its geographical diffusion,
while it covers in the northern temperate zone, as a social plant,
such extensive districts, that we are almost compelled to wonder at
the inconsiderable number of the species. We are not acquainted with
so many Coniferæ by three-fourths as there are Palms already
described, nay, the Coniferæ are numerically less than the Aroideæ.
Zuccarini, in his “Contributions to the Morphology of the
Coniferæ,”[OY] enumerates 216 species, of which 165 belong to the
Northern and 51 to the Southern hemisphere. These proportional numbers
must now, in consequence of my researches, be differently expressed,
since, with the species of Pinus, Cupressus, Ephedra, and Podocarpus,
which Bonpland and I discovered in the tropical part of Peru, Quito,
New Granada, and Mexico, the number of the cone-bearing trees
flourishing between the tropics amounts to 42. The excellent and
latest work of Endlicher[OZ] contains 312 species of Coniferæ now
living, and 178 of a primeval mundane period which are now buried in
the coal formation, in variegated sandstone, in keuper, and in Jura
limestone. The vegetation of the eocene world presents especially to
us forms which, by their coëval relationship with several families of
the present world, remind us that with it many intervening members
have disappeared. The Coniferæ, so frequent in the primeval world,
accompany, in particular, the ligneous remains of Palms and Cycadeæ;
but in the most recent beds of lignite or brown coal we again find
Coniferæ, our Pines and Firs, associated with Cupuliferæ (or
Mastworts), Maples and Poplars.[PA]
If the surface of the earth did not rise to great altitudes within the
tropics, the strikingly characteristic form of acicular-leaved trees
would have remained wholly unknown to the inhabitants of that zone. I
took great pains, in common with Bonpland, to trace out, in the
Mexican Highlands, the _lower_ and _upper_ boundary line of the
Coniferæ and Oaks. The heights, at which both begin to grow (los
Pinales y Encinales, Pineta et Querceta), are hailed with joy by those
who come from the sea coast, because they announce a climate not yet
invaded, as far as experience has hitherto shown, by that mortal
disease called the black vomit (vomito prieto, a form of the yellow
fever). For the oaks, especially the Quercus Xalapensis (one of the
twenty-two Mexican species of oak which we first described), the lower
line of vegetation, on the way from Vera Cruz to the capital of
Mexico, somewhat below the Venta del Encero, is 3048 feet above the
sea. At the western slope of the plateau, between the South Sea and
Mexico, the inferior line for oaks is something lower; it begins near
a hut named Venta de la Moxonera, between Acapulco and Chilpanzingo,
at the absolute height of 2481 feet. I found a similar difference in
the lower boundary line of the pine-forest. This boundary, towards the
South Sea, in the Alto de los Caxones, north of Quaxinquilapa, is for
the Pinus Montezumæ (Lamb.), which we at first had considered to be
the Pinus occidentalis (Swartz), at the height of 4092 feet; but
towards Vera Cruz, at the Cuesta del Soldado, it rises to 5979 feet.
Both these kinds of tree, therefore, the oaks and firs as specified
above, descended lower towards the Pacific than towards the Caribbean
Gulf. During my ascent of the Cofre di Perote, I found the superior
boundary Line of the oaks to be 10,353 feet; that of the Pinus
Montezumæ 12,936 feet (about 2000 feet higher than the summit of Mount
Ætna) and here, in February, considerable masses of snow had already
fallen.
The greater the heights at which the Mexican cone-bearing trees begin
to show themselves, the more singular is it, in the island of Cuba
(where, at the border of the tropical zone the air, it is true, is
cooled down during northerly winds to 46°.6 Fahr.), to see another
kind of fir (_P. Occidentalis_, Swartz), in the plain itself, or on
the gentle hills of the Isle of Pines, growing among palms and
mahogany trees (_Swietenia_). Columbus even makes mention of a
fir-wood (_Pinal_) in the journal of his first voyage (Diario del 25
de Nov., 1492), at Caya de Moya, north-east of Cuba. At Haiti, too
(St. Domingo), the Pinus occidentalis near Cape Samana descends from
the mountains down to the very beach. The stems of these firs, wafted
by the gulf-stream to the two Azores, Graciosa and Fayal, were among
the principal signs that proclaimed to the great discoverer the
existence of unknown lands in the West.[PB] Is it positively
ascertained that the Pinus occidentalis is entirely absent from
Jamaica, notwithstanding its lofty mountains? We may be permitted to
inquire also, what kind of Pinus grows on the eastern coast of
Guatimala, since the P. tenuifolia (Benth.) is assuredly found only on
the mountains near Chinanta.
On taking a general view of the species of plants which form the upper
tree-boundary in the northern hemisphere from the frigid zone to the
equator; I find, for Lapland, according to Wahlenberg, in the
Sulitelma Mountains (lat. 68°), not acicular-leaved trees but birches
(Betula alba), far above the upper limit of the Pinus sylvestris; and
for the temperate zone I find in the Alps (lat. 45° 45′) Pinus picea
(Du Roi), advanced beyond the birches. In the Pyrenees (lat. 42° 30′),
we find Pinus uncinata (Ram.) and P. sylvestris, var. rubra; within
the tropics in Mexico (lat. 19°–20°), Pinus Montezumæ extends far
beyond Alnus toluccensis, Quercus spicata, and Q. crassipes; and in
the snow-crowned mountains of Quito, beneath the equator, Escallonia
myrtilloides, Aralia avicennifolia, and Drymis Winteri attain the
highest limits. This last species of tree, identical with the Drymis
granatensis (Mut.), and the Wintera aromatica of Murray, presents, as
Dr. Joseph Hooker has shown,[PC] the most singular instance of the
uninterrupted dissemination of the same species of tree from the
southernmost part of Tierra del Fuego and Hermit Island, where it was
discovered as early as 1577 by Drake’s expedition, up to the northern
Highlands of Mexico, over a meridian extent of 86° of latitude or 5160
miles. Where the acicular or needle-leaved trees, as in the Swiss Alps
and the Pyrenees, and not the birch as in the extreme north, form the
boundary of arborescent vegetation on the loftiest mountains, which
they picturesquely encircle, they are immediately followed in their
ascent towards the snow-crowned summits, in Europe and Western Asia by
the Alpine roses, Rhododendra, and at the Silla de Caracas, and the
Peruvian Paramo de Saraguru, by the purplish-red blossoms of the
graceful Befariæ. In Lapland the Rhododendron laponicum immediately
follows the Coniferous trees; in the Swiss Alps, the Rhododendron
ferrugineum and R. hirsutum, and in the Pyrenees the R. ferrugineum
alone; and in the Caucasus the R. caucasicum. But R. caucasicum has
also been found isolated by De Candolle in the Jura mountains (in the
Creux de Vent), 5968 feet lower down, at the inconsiderable height of
from 3303 to 3730 feet. If we would trace out the last zone of
vegetation near the snow line we must name, according to our personal
observation, in tropical Mexico, Cnicus nivalis and Chelone
gentianoides; in the cold mountainous tracts of New Granada, the
woolly Espeletia grandiflora, E. corymbosa, and E. argentea; in the
Andes chain of Quito, Culcitium rufescens, C. ledifolium, and C.
nivale;—yellow-blossomed Compositæ, which replace the somewhat more
northerly lanose herbs of New Granada, and the Epeletiæ, with which
they have so much physiognomical resemblance. This substitution or
repetition of similar and almost identical forms in regions that are
separated from each other by seas or wide intervening tracts, is a
wonderful law of nature. It prevails even in the rarest forms of the
floras. In Robert Brown’s family of the Rafflesiæ, separated from the
Cytineæ, the two Hydnoræ in Southern Africa (H. Africana and H.
Triceps), described by Thunberg and Drege, have, in South America,
their counterpart in the H. Americana of Hooker.
Far above the regions of Alpine herbs, of the grasses and the lichens,
nay, beyond the boundary of perpetual snow, there occasionally appears
a phanerogamic plant, growing sporadically, and as it were isolated,
to the astonishment of botanists; and this occurs both within the
tropics and in the temperate zone, on fragments of rock which remain
free from snow and are probably warmed by open fissures. I have
already mentioned the Saxifraga Boussingaulti, which is found at a
height of 15,773 feet on the Chimborazo; in the Swiss Alps the Silene
acaulis, a clovewort or caryophyllea, has been seen at a height of
11,382 feet. The former vegetates at 640, the latter at 2621 feet
above the respective local limits of snow, heights which were
determined when both the plants were discovered.
In our European Coniferous woods the Red Pine (or Norway Spruce), and
the White (or Silver) Pine show great and remarkable variations as
regards their geographical dispersion on the slopes of mountains.
Whilst in the Swiss Alps the Red Pine (_Pinus picea_, Du Roi, _foliis
compressotetragonis_; unfortunately named by Linnæus and by most
botanists of our time the _Pinus abies_!), forms the limit of tree
vegetation at the mean height of 5883 feet, and only here and there
does the lowly alder (_Alnus viridis_, Dec., _Betula viridis_, Vill.),
advance higher towards the snow-limit; the White Pine (_Pinus abies_,
Du Roi, _Pinus picea_, Linn., foliis planis, pectinato-distichis,
emarginatis), has its limit, according to Wahlenberg, about 1000 feet
lower. The Red Pine does not grow at all in Southern Europe, in Spain,
the Apennines, and Greece; and, as Ramond remarks, it is only seen on
the slope of the northern Pyrenees at great heights, and is entirely
wanting in the Caucasus. The Red Pine extends further to the north in
Scandinavia than the White, which latter tree appears in Greece (on
the Parnassus, the Taygetus, and the Œta), as a variety with long
acicular leaves, _foliis apice integris, breviter mucronatis_, the
Abies Apollinis of the acute observer Link.[PD]
On the Himalaya the acicular-leaved form of trees is distinguished by
the mighty thickness and height of the stem as well as by the length
of the leaf. The chief ornament of the mountain range is the Cedar
Deodwara (_Pinus deodara_, Roxb.), which word is, in Sanscrit,
dêwa-dâru, _i.e._ timber for the gods, its stem being nearly from 13
to 14 feet in diameter. It ascends in Nepaul to more than 11,700 feet
above the level of the sea. More than 2000 years ago the Deodwara
cedar near the River Behut, that is, the Hydaspes, furnished the
timber for the fleet of Nearchus. In the valley of Dudegaon, north of
the copper mines of Dhunpoor in Nepaul, Dr. Hoffmeister, so early lost
to science, found in a forest the Pinus longifolia (Royle), or the
Tschelu Fir, mixed with the lofty stems of a palm—Chamærops martiana
(Wallich).[PE] Such an interspersion of the _pineta_ and _palmeta_ had
already, in the new continent, excited the astonishment of the
companions of Columbus, as a friend and contemporary of the admiral’s,
Petrus Martyr Anghiera, relates.[PF] I myself saw, for the first time,
this blending of pines with palms on the road from Acapulco to
Chilpanzingo. The Himalaya, like the Mexican highlands, besides its
genera of pine and cedar, possesses also forms of the Cypress
(_Cupressus torulosa_, Don.); of the Yew (_Taxus Wallichiana_,
Zuccar.); of the Podocarpus (_Podocarpus nereifolia_, Brown); and the
Juniper (_Juniperus squamata_, Don., and _J. excelsa_, Bieberst.; the
latter species occurring also at Schipke in Thibet, in Asia Minor,
Syria, and the Grecian Islands; on the other hand, Thuja, Taxodium,
Larix, and Araucaria, are forms of the New Continent, which are
wanting in the Himalaya.
Besides the twenty species of pine with which we are acquainted in
Mexico, the United States of North America, in their present extension
to the Pacific, present forty-five described species, whilst all
Europe can only enumerate fifteen. The same difference between
abundance and paucity of forms is shown in the oaks, in favour of the
New Continent (a quarter of the world the most connected and most
elongated in a meridional direction). It has, however, been very
recently demonstrated by the extremely accurate researches of Siebold
and Zuccarini to be an erroneous assertion, that many European species
of pine, in consequence of their wide distribution throughout Northern
Asia, passed over to the Japanese islands, and there mingled with a
genuine Mexican species, the Weymouth pine (_Pinus strobus_, L.), as
Thunberg asserts. What Thunberg considered to be European species of
pine, are species entirely different. Thunberg’s Red Pine (_Pinus
abies_, Linn.) is _P. polita_, Sieb., and often planted near Buddhist
temples; his northern common fir (_Pinus sylvestris_) is P.
Massoniana, Lamb.; his P. cembra, the German and Siberian stone
pine-tree, is P. parviflora, Sieb.; his common larch (_P. larix_) is
the P. leptolepis, Sieb.; his Taxus baccata, the fruit of which the
Japanese courtiers eat as a precautionary measure when attending long
ceremonies,[PG] forms a special genus and is Cephalotaxus drupacea,
Sieb. The Japanese islands, despite the proximity of the Asiatic
Continent, have a very different character of vegetation. Thunberg’s
Japanese Weymouth pine, which would present an important phenomenon,
is moreover a naturalized tree, that differs entirely from the
indigenous pines of the New World. It is Pinus korajensis, Sieb.,
which has migrated from the peninsula of Corea and Kamtschatka to
Nipon.
Of the 114 species now known of the genus Pinus, there is not one in
the whole southern hemisphere, for the Pinus Merkusii, described by
Junghuhn and De Vriese, still belongs to that part of the island of
Sumatra which is north of the equator, that is, to the district of the
Battas. The P. insularis, Endl., belongs to the Philippines, although
at first it was introduced into Loudon’s _Arboretum_ as P.
timoriensis. From our present increasing knowledge of the geography of
plants, we know that there are excluded also from the southern
hemisphere, in addition to the genus Pinus, all the races of
Cupressus, Salisburia (_Ginkgo_), Cunninghamia (_Pinus lanceolata_,
Lamb.), Thuja, one species of which (_Th. gigantea_, Nutt.) at the
Columbia river rises as high as 180 feet, Juniperus, and Taxodium
(Mirbel’s _Schubertia_). I can introduce this last genus here with the
greater certainty, inasmuch as a Cape plant, Sprengel’s Schubertia
capensis, is no Taxodium, but forms a special genus, Widringtonia,
Endl., in quite another division of the Coniferæ.
This absence from the southern hemisphere of the true Abietineæ, of
the Juniperineæ, Cupressineæ, and all the Taxodineæ, as likewise of
the Torreya, of the Salisburia adiantifolia, and of the Cephalotaxus
among the Taxineæ, vividly reminds us of the enigmatical and still
obscure conditions which determined the original distribution of
vegetable forms. This distribution can by no means be satisfactorily
explained either by the similarity or diversity of the soil, by
thermal relations, or by meteorological conditions. I have long since
directed attention to the fact, that the southern hemisphere
possesses, for instance, many plants of the natural family of the
Rosaceæ, but not a single species of the genus Rosa itself. Claude Gay
informs us, that the Rosa Chilensis, described by Meyen, is a variety
that has become wild of the Rosa centifolia, Linn., which has been
naturalized in Europe for thousands of years. Such wild-growing
varieties occupy large tracts in Chili near Valdivia and Osorno.[PH]
In the whole tropical region of the northern hemisphere we only found
one single indigenous rose, our Rosa Montezumæ, and this was on the
Mexican highland, near Moran, at a height of 9336 feet. We may count
among the strange phenomena observed in the distribution of plants,
the total absence of the Agave from Chili, though it possesses Palms,
Pourretias, and many species of Cactus; and although A. americana
flourishes luxuriantly in Roussillon, at Nice, at Botzen, and in
Istria, where it was probably introduced from the New Continent since
the sixteenth century, and where it forms one connected line of
vegetation from the north of Mexico, across the isthmus of Panama, as
far as Southern Peru. With respect to the Calceolarias, I long
believed that, like the roses, they were only to be found exclusively
on the northern side of the equator. In fact, among the twenty-two
species that we brought with us, not one was gathered to the north of
Quito and the volcano of Pichincha; but my friend Professor Kunth
remarks that Calceolaria perfoliata, which Boussingault and Capt. Hall
found near Quito, advances also as far as New Granada, and that this
species, as well as C. integrifolia, was sent by Mutis from Santa Fé
de Bogotá to the great Linnæus.
The species of Pinus, which are so abundant in the wholly
inter-tropical Antilles, as well as in the tropical mountain regions
of Mexico, do not cross the isthmus of Panama, and are wholly wanting
in the equally mountainous parts of tropical South America, that lie
north of the equator; they are equally unknown on the elevated plains
of New Granada, Pasto, and Quito. I have advanced in the plains and on
the mountains from the Rio Sinu, near the isthmus of Panama, as far as
12° south lat.; and in this territorial extent, of nearly 1600 miles
in length, the only forms of needle-leaved trees that I saw, were the
taxoid Podocarpus (P. taxifolia), 64 feet high, in the Andes pass of
Quindiu and in the Paramo de Saraguru, in 4° 26′ north and 3° 40′
south latitude, and an Ephedra (E. americana) near Guallabamba, north
of Quito.
Among the group of the Coniferæ, the following are common to the
northern and southern hemispheres: Taxus, Gnetum, Ephedra, and
Podocarpus. Long before l’Heritier, the last genus had been very
properly distinguished from Pinus by Columbus on the 25th of November,
1492. He says, “Pinales en la Serrania de Haiti que no llevan piñas,
pero frutos que parecen azeytunos del Axarafe de Sevilla.”[PI] Species
of yew extend from the Cape of Good Hope to 61° north lat. in
Scandinavia, consequently through more than 95 degrees of latitude.
Podocarpus and Ephedra are almost as widely distributed; and even from
among the Cupuliferæ, the species of the oak genus, usually termed by
us a northern form, though they do not cross the equator in South
America, reappear in the southern hemisphere, at Java, in the Indian
archipelago. To this latter hemisphere ten genera of the cone-bearing
trees exclusively appertain, of which we will here cite only the most
important: Araucaria, Dammara (_Agathis_, Sal.), Frenela (comprising
about 18 Australian species), Dacrydium and Lybocedrus, whose habitat
is both in New Zealand and the Straits of Magellan. New Zealand
possesses one species of the genus Dammara (_D. australis_), but no
Araucaria. The contrary, by a singular contrast, is the case in New
Holland.
In the form of acicular-leaved trees, Nature presents us with the
greatest length of stem existing in arborescent productions. I use the
term arborescent, for, as we have already remarked, among the
Laminariæ (the oceanic algæ) Macrocystis pyrifera, between the coast
of California and 68° south lat., often attains a length of more than
400 feet. If we exclude the six Araucarias of Brazil, Chili, New
Holland, the Norfolk Islands and New Caledonia, then those Coniferæ
are the highest, whose habitat is the temperate zone of the North. As
we have found among the family of the palms the most gigantic of all,
the Ceroxylon andicola, about 192 feet high, in the temperate Alpine
climate of the Andes, so in like manner do the loftiest cone-bearing
trees belong, in the _northern_ hemisphere, to the temperate
north-western coast of America and to the Rocky Mountains (lat. from
40° to 52°), in the _southern_ hemisphere to New Zealand, Tasmania or
Van Dieman’s Land, to Southern Chili and Patagonia, (where the lat. is
again from 43° to 50°). The most gigantic forms among the genus Pinus
are Sequoia (Endl.), Araucaria, and Dacrydium. I only name those
species whose height not merely reaches but often exceeds 200 feet.
That the reader may have a standard of comparison, he is reminded that
in Europe the loftiest Red and White Pines, especially the latter,
reach a height of from 160 to 170 feet; for instance, in Silesia, the
pine in the Lampersdorf forest, near Frankenstein, long famous for its
altitude, is only 158 feet high, although 17 feet in girth.[PJ]