given by the Venetian Aloysius Cadamosto (the real name was Alvise da
Ca da Mosto), in 1454. He found at the mouth of the Senegal, trunks
of which he estimated the circumference at seventeen fathoms, or 102
feet, (Ramusio, Vol. i. p. 109): he might have compared them with
Dragon trees which he had seen before. Perrottet says in his “Flore de
Sénégambie” (p. 76), that he had seen monkey bread-trees which, with
a height of only about 70 or 80 feet, had a diameter of 32 English
feet. The same dimensions had been given by Adanson, in the account
of his voyage in 1748; the largest trunks which he himself saw (in
1749) in one of the small Magdalena islands near Cape de Verd, and
in the vicinity of the mouth of the Senegal River, were from 26 to
28-1/2 English feet in diameter, with a height of little more than 70
feet, and a top about 180 feet broad; but he adds at the same time,
that other travellers had found trunks of nearly 32 English feet
diameter. French and Dutch sailors had cut their names on the trees
seen by Adanson in letters half a foot long; the dates added to the
names shewed these inscriptions to be all of the 16th century, except
one which belonged to the 15th. (In Adanson’s “Familles des Plantes,”
1763, P. I. pp. ccxv.-ccxviii., it stands as the 14th century, but
this is doubtless an error of inadvertence.) From the depth of the
inscriptions, which were covered with new layers of wood, and from the
comparison of the thickness of different trunks of the same species
in which the relative age of the trees was known, Adanson computed
the probable age of the larger trees, and found for a diameter of 32
English feet 5150 years. (Voyage au Sènegal, 1757, p. 66.) He prudently
adds (I do not alter his curious orthography):--“Le calcul de l’aje
de chake couche n’a pas d’exactitude géometrike.” In the village of
Grand Galarques, also in Senegambia, the negroes have ornamented the
entrance of a hollow Baobab tree with sculptures cut out of the still
fresh wood; the interior serves for holding meetings in which their
interests are debated. Such a hall of assembly reminds one of the
hollow or cave (specus) of the plane tree in Lycia, in which Lucinius
Mutianus, who had previously been consul, feasted with twenty-one
guests. Plino (xii. 8) assigns to such a cavity in a hollow tree
the somewhat large allowance of a breadth of eighty Roman feet. The
Baobab was seen by Réné Caillié in the Valley of the Niger near Jenne,
by Caillaud in Nubia, and by Wilhelm Peters along the whole eastern
coast of Africa (where it is called Mulapa, _i. e._ Nlapa-tree, more
properly Muti-nlapa) as far as Lourenzo Marques, almost to 26° of S.
lat. Although Cadamosto said in the 15th century “eminentia non quadrat
magnitudini,” and although Golberry (Fragmens d’un Voyage en Afrique,
T. ii. p. 92) found in the “Vallée des deux Gagnacks” trunks which,
with 36 English feet diameter near the roots, were only 64 English feet
high, yet this great disproportion between height and thickness must
not be regarded as general. The learned traveller Peters remarks that
“very old trees lose height by the gradual decay of the top, while they
continue to increase in girth. On the East Coast of Africa one sees
not unfrequently trunks of little more than ten feet diameter reach a
height of 69 English feet.”
If, according to what has been said, the bold estimations of Adanson
and Perottet assign to the Adansonias measured by them an age of from
5150 to 6000 years, which would make them contemporaneous with the
epoch of the building of the Pyramids or even with that of Menes, a
period when the constellation of the Southern Cross was still visible
in Northern Germany (Kosmos, Bd. iii. S. 402 and 487; Eng. ed. p. 293,
and note 146), on the other hand, the more secure estimations made
from the annual rings of trees in our northern temperate zone, and
from the ratio which has been found to subsist between the thickness
of the layer of wood and the time of growth, give us shorter periods.
Decandolle finds as the result of his inquiries, that of all European
species of trees the yew is that which attains the greatest age. He
assigns to the yew (Taxus baccata) of Braborne, in the county of Kent,
thirty centuries; to the Scotch yew of Fortingal, from twenty-five
to twenty-six; and to those of Crowhurst in Surrey, and Ripon in
Yorkshire, respectively, fourteen and a half and twelve centuries.
(Decandolle, de la longévité des arbres, p. 65.) Endlicher remarks
that the age of another yew tree, in the Churchyard of Grasford, in
North Wales, which measures 52 English feet in circumference below the
branches, is estimated at 1400 years, and that of a yew in Derbyshire
at 2096 years. In Lithuania lime trees have been cut down which were 87
English feet in circumference, and in which 815 annual rings have been
counted. (Endlicher, Grundzüge der Botanik, S. 399.) In the temperate
zone of the southern hemisphere some species of Eucalyptus attain an
enormous girth, and as they also reach to a great stature (above 230
Paris, 245 English, feet), they are singularly contrasted with our yew
trees, whose great dimension is in thickness only. Mr. Backhouse found
in Emu Bay, on the coast of Van Diemen Land, trunks of Eucalyptus which
measured 70 English feet round the trunk near the ground, and five feet
higher up 50 English feet. (Gould, Birds of Australia, Vol. I. Introd.
p. xv.)
It is not, as is commonly stated, Malpighi, but the ingenious Michel
Montaigne, who has the merit of having been the first, in 1581, in his
Voyage en Italie, to notice the relation of the annual rings to the age
of the tree. (Adrien de Jussieu, Cours élémentaire de Botanique, 1840,
p. 61.) A skilful artist, engaged in the preparation of astronomical
instruments, had called the attention of Montaigne to the annual
rings; and he also maintained that the rings were narrower on the north
side of the tree. Jean Jacques Rousseau had the same belief; and his
Emile, if he loses himself in a forest, is to direct himself by the
indications afforded by the relative thickness of the layers of wood.
More recent observations on the anatomy of plants teach us, however,
that both the acceleration and also the retardation or intermission
of growth, or the varying production of circles of ligneous fascicles
(annual deposits) from the Cambium cells, depend on influences which
are wholly distinct from the quarter of the heavens towards which one
side of the annual rings is turned. (Kunth, Lehrbuch der Botanik, 1847,
T. i. S. 146 and 164; Lindley, Introduction to Botany, 2d edition, p.
75.)
Trees which in individual cases attain a diameter of more than twenty
feet, and an age extending to many centuries, belong to the most
different natural families. I may name here Baobabs, Dragon-trees, some
species of Eucalyptus, Taxodium disticum (Rich.), Pinus Lambertiana
(Douglas), Hymenæa courbaril, Cæsalpinieæ, Bombax, Swietenia mahagoni,
the Banyan tree (Ficus religiosa), Liriodendron tulipifera? Platanus
orientalis, and our Limes, Oaks, and Yews. The celebrated Taxodium
distichon, the Ahuahuete of the Mexicans, (Cupressus disticha Linn.,
Schubertia disticha Mirbel); at Santa Maria del Tule, in the state
of Oaxaca, has not a diameter of 57, as Decandolle says, but of
exactly 38 French (40-1/2 English) feet. (Mühlenpfordt, Versuch einer
getreuen Schilderung der Republik Mexico, Bd. i. S. 153.) The two fine
Ahuahuetes near Chapoltepec, which I have often seen, and which are
probably the surviving remnants of an ancient garden or pleasure-ground
of Montezuma, measure, (according to Burkart’s account of his travels,
Bd. i. S. 268, a work which otherwise contains much information),
only 36 and 38 English feet in circumference; not in diameter, as has
often been erroneously asserted. The Buddhists in Ceylon venerate the
gigantic trunk of the sacred fig-tree of Anourahdepoura. The Indian
fig-tree or Banyan, of which the branches take root round the parent
stem, forming, as Onesicritus well described, a leafy canopy resembling
a many-pillared tent, often attain a thickness of 28 (29-1/2 English)
feet diameter. (Lassen, Indische Alterthumskunde, Bd. i. S. 260.) On
the Bombax ceiba, see early notices of the time of Columbus, in Bembo’s
Historiæ Venetæ, 1551, fol. 83.
Among oak-trees, of those which have been accurately measured, the
largest in Europe is no doubt that near the town of Saintes, in the
Departement de la Charente Inférieure, on the road to Cozes. This
tree, which is 60 (64 English) feet high, has a diameter of 27 feet
8-1/2 inches (29-1/2 English feet) near the ground; 21-1/2 (almost 23
English) feet five feet higher up; and where the great boughs commence
6 Parisian feet (6 feet 5 inches English.) In the dead part of the
trunk a little chamber has been arranged, from 10 feet 8 inches to 12
feet 9 inches wide, and 9 feet 8 inches high (all English measure),
with a semi-circular bench cut out of the fresh wood. A window gives
light to the interior, so that the sides of the chamber (which is
closed with a door) are clothed with ferns and lichens, giving it a
pleasing appearance. Judging by the size of a small piece of wood which
has been cut out above the door, and in which the marks of 200 annular
rings have been counted, the oak of Saintes would be between 1800 and
2000 years old. (Annales de la Société d’Agriculture de la Rochelle,
1843, p. 380.)
In the wild rose-tree of the crypt of the Cathedral of Hildesheim, said
to be a thousand years old, it is the root only, and not the stem,
which is eight centuries old, according to accurate information derived
from ancient and trustworthy original documents, for the knowledge of
which I am indebted to the kindness of Stadtgerichts-Assessor Römer. A
legend connects the rose-tree with a vow made by the first founder of
the cathedral, Ludwig the Pious; and an original document of the 11th
century says, “that when Bishop Hezilo rebuilt the cathedral which
had been burnt down, he enclosed the roots of the rose-tree with a
vault which still exists, raised upon this vault the crypt, which was
re-consecrated in 1061, and spread out the branches of the rose-tree
upon the walls.” The stem now living is 26-1/2 feet high and about two
inches thick, and the outspread branches cover about 32 feet of the
external wall of the eastern crypt; it is doubtless of considerable
antiquity, and well deserving of the celebrity which it has gained
throughout Germany.
If extraordinary development in point of size is to be regarded as
a proof of long continued organic life, particular attention is due
to one of the thalassophytes of the sub-marine vegetable world, _i.
e._, to the Fucus giganteus, or Macrocystis pyrifera of Agardh.
According to Captain Cook and George Forster, this sea-plant attains
a length of 360 English feet; surpassing, therefore, the height of
the loftiest Coniferæ, even that of the Sequoia gigantea, Endl., or
Taxodium sempervirens, Hook and Arnott, which grows in California.
(Darwin, Journal of Researches into Natural History, 1845, p. 239;
and Captain Fitz-Roy in the Narrative of the Voyages of the Adventure
and Beagle, vol. ii. p. 363.) Macrocystis pyrifera is found from 64°
south to 45° north latitude, as far as San Francisco on the north-west
coast of America; and Joseph Hooker believes it to extend as far as
Kamtschatka. In the Antarctic seas it is even seen floating among the
pack-ice. (Joseph Hooker, Botany of the Antarctic Voyage under the
command of Sir James Ross, 1844, pp. 7, 1, and 178; Camille Montagne,
Botanique cryptogame du Voyage de la Bonite, 1846, p. 36.) The immense
length to which the bands or ribbands and the cords or lines of the
cellular tissue of the Macrocystis attain, appears to be limited only
by accidental injuries.
[13] p. 17.--“_Species of phænogamous plants already contained in
herbariums._”
We must carefully distinguish between three different questions:
How many species of plants are described in printed works? how many
have been discovered, _i. e._ are contained in herbariums, though
without being described? how many are probably existing on the
globe? Murray’s edition of the Linnean system contains, including
cryptogamia, only 10042 species. Willdenow, in his edition of the
Species Plantarum, between the years 1797 and 1807, had already
described 17457 phænogamous species, (from Monandria to Polygamia
diœcia.) If we add 3000 cryptogamous species, we obtain the number
which Willdenow mentions, viz. 20000 species. More recent researches
have shown how much this estimation of the number of species described
and contained in herbariums falls short of the truth. Robert Brown
counted above 37000 phænogamous plants. (General Remarks on the
Botany of Terra Australis, p. 4.) I afterwards attempted to give the
geographical distribution (in different parts of the earth already
explored), of 44000 phænogamous and cryptogamous plants. (Humboldt,
de distributione geographica Plantarum, p. 23.) Decandolle found,
in comparing Persoon’s Enchiridium with his Universal System in
12 several families, that the writings of botanists and European
herbariums taken together might be assumed to contain upwards of
56000 species of plants. (Essai élementaire de Géographie botanique,
p. 62.) If we consider how many species have since that period been
described by travellers,--(my expedition alone furnished 3600 of the
5800 collected species of the equinoctial zone),--and if we remember
that in all the botanical gardens taken together there are certainly
above 25000 phænogamous plants cultivated, we shall easily perceive
how much Decandolle’s number falls short of the truth. Completely
unacquainted as we still are with the larger portions of the interior
of South America,--(Mato-Grosso, Paraguay, the eastern declivity of
the Andes, Santa Cruz de la Sierra, and all the countries between
the Orinoco, the Rio Negro, the Amazons, and Puruz),--of Africa,
Madagascar, Borneo, and Central and Eastern Asia,--the thought rises
involuntarily in the mind that we may not yet know the third, or
probably even the fifth part of the plants existing on the earth!
Drège has collected 7092 species of phænogamous plants in South Africa
alone. (See Meyer’s pflanzen geographische Documente, S. 5 and 12.) He
believes that the Flora of that district consists of more than 11000
phænogamous species, while on a surface of equal area (12000 German,
or 192000 English square geographical miles) von Koch has described
in Germany or Switzerland 3300, and Decandolle in France 3645 species
of phænogamous plants. I would also recall that even now new Genera,
(some even consisting of tall forest trees), are being discovered in
the small West Indian Islands which have been visited by Europeans
for three centuries, and in the vicinity of large commercial towns.
These considerations, which I propose to develop in further detail
at the close of the present annotation, make it probable that the
actual number of species exceeds that spoken of in the old myth of the
Zend-Avesta, which says that “the Primeval Creating Power called forth
from the blood of the sacred bull 120000 different forms of plants!”
If, then, we cannot look for any direct scientific solution of the
question of how many forms of the vegetable kingdom,--including
leafless Cryptogamia (water Algæ, funguses, and lichens), Characeæ,
liver-worts, mosses, Marsilaceæ, Lycopodiaceæ, and ferns,--exist on
the dry land and in the ocean in the present state of the organic
life of our globe, we may yet attempt an approximate method by which
we may find some probable “lowest limits” or numerical minima. Since
1815, I have sought, in arithmetical considerations relating to the
geography of plants, to examine first the ratios which the number
of species in the different natural families bear to the entire
mass of the phænogamous vegetation in countries where the latter is
sufficiently well known. Robert Brown, the greatest botanist among our
cotemporaries, had previously determined the numerical proportions
of the leading divisions of the vegetable kingdom; of Acotyledons
(Agamæ, Cryptogamic or cellular plants) to Cotyledons (Phanerogamic
or vascular plants), and of Monocotyledonous (Endogenous) to
Dicotyledonous (Exogenous) plants. He finds the ratio of Monocotyledons
to Dicotyledons in the tropical zone as 1 : 5, and in the cold zones
of the parallels of 60° N. and 55° S. latitude, as 1 : 2-1/2. (Robert
Brown, General Remarks on the Botany of Terra Australis, in Flinders’
Voyage, vol. ii. p. 338.) The absolute number of species in the three
leading divisions of the vegetable kingdom are compared together in
that work according to the method there laid down. I was the first
to pass from these leading divisions to the divisions of the several
families, and to consider the ratio which the number of species of
each family bears to the entire mass of phænogamous plants belonging
to a zone of the earth’s surface. (Compare my memoir entitled De
distributione geographica Plantarum secundum cœli temperiem et
altitudinem montium, 1817, p. 24-44; and the farther development of the
subject of these numerical relations given by me in the Dictionnaire
des Sciences naturelles, T. xviii. 1820, p. 422-436; and in the Annales
de Chimie et de Physique, T. xvi. 1821, p. 267-292.)
The numerical relations of the forms of plants, and the laws observed
in their geographical distribution, may be considered in two very
different ways. If plants are studied in their arrangement according to
natural families, without regard to their geographical distribution,
it is asked, What are the fundamental forms or types of organisation
to which the greatest number of species correspond? Are there on the
entire surface of the earth more Glumaceæ than Compositæ? Do these
two orders make up between them one-fourth part of the whole number
of phænogamous plants? What is the proportion of Monocotyledons to
Dicotyledons? These are questions of General Phytology, or of the
science which investigates the organisation of plants and their mutual
connection, or the present state of the entire vegetable world.
If, on the other hand, the species of plants which have been grouped
according to the analogy of their structure are considered, not
abstractedly, but according to their climatic relations, or according
to their distribution over the surface of the earth, we have questions
offering quite another and distinct interest. We then examine what are
the families which prevail more in proportion to other Phanerogamæ
in the torrid zone than towards the polar circle? Are Compositæ more
numerous, either in the same geographical latitudes or on the same
isothermal lines, in the New than in the Old Continent? Do the forms
which gradually lose their predominance in advancing from the equator
towards the poles follow a similar law of decrease in ascending
mountains situated in the equatorial regions? Do the proportions of
particular families to the whole mass of Phanerogamæ differ in the
temperate zones, and on equal isothermal lines, north and south of the
equator? These questions belong properly to the Geography of Plants,
and connect themselves with the most important problems of meteorology
and terrestrial physics. The character of a landscape or country is
also in a high degree dependent on the predominance of particular
families of plants, which render it either desolate or adorned, smiling
or majestic. Grasses forming extensive savannahs, Palms and other trees
affording food, or social Coniferæ forming forests, have powerfully
influenced nations in respect to their material condition, to their
manners, to their mental dispositions, and to the more or less rapid
development of their prosperity.
In studying the geographical distribution of forms, we may consider
species, genera, and natural families, separately. In social plants, a
single species often covers extensive tracts of country; as in northern
regions forests of Pines or Firs and extensive heaths (ericeta), in
Spain cistus-covered grounds, and in tropical America assemblages of
the same species of Cactus, Croton, Brathys, or Bambusa Guadua. It is
interesting to examine these relations more closely, and to view in
one case the great multiplicity of individuals, and in another the
variety of organic development. We may inquire what species produces
the greatest number of individuals in a particular zone, or we may
ask which are the families to which, in different climates, the
greatest number of species belong. In a high northern region, where the
Compositæ and the Ferns are to the sum of all the phænogamous plants
in the ratio of 1 : 13 and 1 : 25 (_i. e._ where these ratios are
found by dividing the sum total of all the Phanerogamæ by the number
of species belonging to the family of Compositæ or to that of Filices
or Ferns), it may nevertheless happen that a single species of fern
covers ten times more ground than do all the species of Compositæ taken
together. In this case Ferns predominate over Compositæ by their mass,
or by the number of individuals belonging to the same species of Pteris
or Polypodium; but they do not so predominate if we only compare the
number of the different specific forms of Filices and Compositæ with
the sum of all the phænogamous plants. Since, then, multiplication of
plants does not follow the same law in all species,--that is to say,
all species do not produce the same number of individuals,--therefore
the quotients given by dividing the sum of the phænogamous plants
by the number of species belonging to one family, do not suffice
by themselves to determine the character of the landscape, or the
physiognomy which Nature assumes in different regions of the earth. If
the attention of the travelling botanist is engaged by the frequent
repetition of the same species, their mass, and the uniformity of
vegetation thus produced, it is even more arrested by the rarity or
infrequency of several other species which are valuable to mankind.
In tropical regions, where the Rubiaceæ, Myrtaceæ, Leguminosæ, or
Terebinthaceæ, form forests, one is astonished to find the trees of
Cinchona, particular species of Swietenia (Mahogany), Hæmatoxylon,
Styrax, and balsamic Myroxylum, so sparingly distributed. We had
occasion, on the declivities of the high plains of Bogota and Popayan,
and in the country round Loxa, in descending towards the unhealthy
valley of the Catamayo and to the Amazons River, to remark the manner
in which the trees which furnish the precious fever-bark (species of
Cinchona) are found singly and at considerable distances from each
other. The China Hunters, Cazadores de Cascarilla (the name given
at Loxa to the Indians and Mestizoes who collect each year the most
efficacious of all fever-barks, that of the Cinchona Condaminea, among
the lonely mountains of Caxanuma, Uritusinga, and Rumisitana), climb,
not without peril, to the summits of the loftiest forest trees in
order to gain a wide prospect, and to discern the solitarily scattered
slender aspiring trunks of the trees of which they are in search, and
which they recognise by the shining reddish tint of their large leaves.
The mean temperature of this important forest region, situated in 4°
to 4-1/2° S. lat. and at an elevation of about 6400 to 8000 English
feet, is from 12-1/2° to 16° Réaumur (60°·2 to 68° Fahr.) (Humboldt and
Bonpland, Plantes équinoxiales, T. i. p. 88, tab. 10.)