American Vegetation—Flora of North, Central, and South America—Antarctic
Flora—Origin and Distribution of the Cerealia—Ages of Trees—Marine
Vegetation.
FROM similarity of physical circumstances the arctic flora of America
bears a strong resemblance to that of the northern regions of Europe and
Asia. This botanical district comprises Greenland, and extends
considerably to the south of the arctic circle, especially at the
eastern and western ends of the continent, where it reaches the 60th
parallel of N. lat., and even more; it is continued along the tops of
the Rocky Mountains almost to Mexico, and it re-appears on the White
Mountains and a few other parts of the Alleghanies.
Greenland has a much more arctic flora than Iceland; the valleys are
entirely covered with mosses and marsh-plants, and the gloomy rocks are
cased in sombre lichens that grow under the snow, and the grasses on the
pasture-grounds that line the fiords are nearly four times less varied
than those of Iceland. In some sheltered spots the service-tree bears
fruit, and birches grow to the height of a few feet: but ligneous plants
in general trail on the ground.
The arctic flora of America has much the same character with that of
Europe and Asia, and many species are common to all; still more are
representative, but there is a difference in the vegetation at the two
extremities of the continent; there are 30 species in the east and 20 in
the west end which grow nowhere else. The sameness of character changes
with the barren treeless lands at the verge of the Arctic region, and
the distribution of plants varies both with the latitude and the
longitude. Taking a broad view of the botanical districts of North
America, there are two woody regions, one on the eastern, the other on
the western side of the continent, separated by a region of prairies
where grasses and herbaceous plants predominate. The vegetation of these
three parts, so dissimilar, varies with the latitude, but not after the
same law as in Europe, for the winter is much colder and the summer
warmer on the eastern coasts of America than on the western coast of
Europe, owing, in a great measure, to the prevalence of westerly winds
which bring cold and damp to our shores.
Boundless forests of black and white spruce, with an undergrowth of
reindeer moss, cover the country south of the Arctic region, which are
afterwards mixed with other trees; gooseberries, strawberries, currants,
and some other plants thrive there. There are vast forests in Canada of
pines, oak, ash, hickory, red beech, birch, the lofty Canadian poplar,
sometimes 100 feet high and 36 feet in circumference, and sugar-maple;
the prevailing plants are Kalmias, azaleas, and asters, the former
vernal, the latter autumnal; solidagos and asters are the most
characteristic plants of this region.
The splendour of the North American flora is displayed in the United
States; the American sycamore, chestnut, black walnut, hickory, white
cedar, wild cherry, red birch, locust-tree, tulip-tree, or Liriodendron,
the glory of American forests, liquid-ambar, oak, ash, pine-trees of
many species, grow luxuriantly, with an undergrowth of rhododendrons,
azaleas, Andromedas, Gerardias, Calycanthus, Hydrangea, and many more of
woody texture, with an infinite variety of herbaceous and climbing
plants.
The vegetation is different on the two sides of the Alleghany mountains;
the locust-tree, Canadian poplar, Hibiscus, and Hydrangea, are most
common on the west side; the American chestnut and Kalmias are so
numerous on the Atlantic side as to give a distinctive character to the
flora: here, too, aquatic plants are more frequent; among these the
Sarracenia or side-saddle flower, singular in form, with leaves like
pitchers covered with a lid, half full of water.
The autumnal tints of the forests in the middle States are beautiful and
of endless variety; the dark leaves of the evergreen pine, the red
foliage of the maple, the yellow beech, the scarlet oak, and purple
Nyssa, with all their intermediate tints, ever changing with the light
and distance, produce an effect at sunset that would astonish the native
of a country with a more sober-coloured flora under a more cloudy sky.
In Virginia, Kentucky, and the southern States, the vegetation assumes a
different aspect, though many plants of more northern districts are
mixed with it. Trees and shrubs here are remarkable for broad shining
leaves and splendid blossoms, as the Gleditschia, Catalpa, Hibiscus, and
all the family of Magnolias, which are natives of the country, excepting
a very few found in Asia and the Indian islands. They are the
distinguishing feature of the flora from Virginia to the Gulf of Mexico,
and from the Atlantic to the Rocky Mountains: the Magnolia grandiflora
and the tulip-tree are the most splendid specimens of this race of
plants; the latter is often 120 feet high. The long-leaved pitch-pine,
one of the most picturesque of trees, covers an arid soil on the coast
of the Atlantic of 60,000 square miles. The swamps so common in the
southern States are clothed with gigantic deciduous cypress, the aquatic
oak, swamp hickory, with the magnificent Nelumbium luteum and other
aquatics, and among the innumerable herbaceous plants the singular
Dionæa muscipula, or American fly-trap: the trap is formed by two
opposite lobes of the leaf, covered with spines, and so irritable, that
they instantly close upon the insect that has come to light upon them.
This Magnolia region corresponds in latitude with the southern shores of
the Mediterranean, but the climate is hotter and more humid, in
consequence of which there is a considerable number of Mexican plants. A
few dwarf-palms appear among the Magnolias, and the forests in Florida
and Alabama are covered with Tillandsia usneoides, an air-plant, which
hangs from the boughs.[164]
Ten or twelve species of grass cover the extensive prairies or steppes
of the valley of the Mississippi. The forms of the Tartarian steppes
appear to the north in the Centaurea, Artemisia, Astragali; but the
Dahlias, Œnotheras, with many more, are their own. The Helianthus and
Coreopsis, mixed with some European genera, mark the middle regions; and
in the south, towards the Rocky Mountains, Clarkia and Bartonia are
mixed with the Mexican genera of Cactus and Yucca. The western forest is
less extensive and less varied than the eastern, but the trees are
larger. This flora in high latitudes is but little known; the Thuia
gigantea on the Rocky Mountains and the coast of the Pacific is 200 feet
high. Claytonias and currants, with plants of northern Asia, are found
here.
Farther west, the Pinus Lambertiana is another specimen of the
stupendous trees of this flora; seven species of pine are indigenous in
California, some of which have measured 200, and even 300 feet high, and
80 in circumference. Captain Sir Edward Belcher, in his “Voyage on the
Pacific,” mentions having measured an oak 27 feet in circumference, and
another 18 feet girth at the height of 60 feet from the ground, before
the branches began to spread. This is the native soil of the
currant-bushes with red and yellow blossoms, of many varieties of
lupins, pæonies, poppies, and other herbaceous plants so ornamental in
our gardens.
There are 332 genera of plants peculiar to North America, exclusive of
Mexico, but no family of any great extent has yet been discovered there.
About 160 large trees yield excellent timber; the wood of the pine-trees
of the eastern forests is of inferior quality to that grown on the other
side of the continent, and both appear to be less valuable than the
pine-wood of Europe, which is best when produced in a cold climate. The
Pinus Cembra and the Pinus uncinata are the most esteemed of the Old
World.
The native fruits of North America are mostly of the nut-kind, and there
are many of these, to which may be added the Florida orange, the Chicasa
plum, the papaw, the banana, the red mulberry, and the plumlike fruit of
the persimon. There are seven species of wild grapes, but good wine has
not hitherto been produced. Although America has contributed so much to
the ornament of our pleasure-grounds and gardens, yet there are
comparatively few North American plants which have become an object of
extensive cultivation, while America has borrowed largely from other
parts of the globe; the grapes cultivated in North America are European;
tobacco, Indian corn, and many others of the utmost commercial value are
strangers to the soil, having been introduced by the earliest
inhabitants from Mexico and South America, which have contributed much
more to general utility.
FLORA OF MEXICO AND THE WEST INDIES.
Mexico itself unites the vegetation of North and South America, though
it resembles that of the latter more nearly. Whole provinces on the
table-land and mountains produce alpine plants, oaks, chestnuts, and
pines spontaneously. The Cheirostemon, or hand-tree, so named from the
resemblance its stigma bears to the human hand, grows here, and also in
the Guatemala forests.
The low lands of Mexico and Central America have a very rich flora,
consisting of many orders and genera peculiar to them, and species
without number, a great portion of which are unknown. The Hymenea
Courbaril, from which the copal of Mexico is obtained, logwood,
mahogany, and many other large trees, valuable for their timber, grow in
the forests; sugar-cane, tobacco, indigo, American aloe, yam, capsicum,
and yucca, are indigenous in Mexico and Central America. It is the
native region of the Melastomas, of which 620 species are known; almost
all the pepper tribe, the Passifloræ, the ornament and pride of tropical
America and the West Indian islands, begin to be numerous in these
regions. The pine-apple is entirely American, growing in the woods and
savannahs: it has been carried to the West Indies, to the East Indies
and China, and is naturalized in all. This country has also produced the
cherimoya, said to be the most exquisite of fruits. All the vanilla that
is used in Europe comes from the States of Vera Cruz and Oaxaca, on the
eastern slopes of the Cordillera of Anahuac in Mexico. It is native
throughout tropical America, growing in hot, damp, shady places. Hot
arid tracts are covered with the Cactus tribe, a family of Central
America and Mexico, which is more widely dispersed than the anana: some
species bear a considerable degree of cold. They are social plants,
inhabiting sandy plains in thickets, and of many species: their forms
are various, and their blossoms beautiful. A few occur at a considerable
distance from the tropics, to the north and the south. The
night-flowering Cereus grows in all its beauty in the arid parts of
Chile, filling the night air with its perfume. The Cactus opuntia grows
in the Rocky Mountains; and Sir George Back found a small island in the
Lake of the Woods covered with it. This species has been brought to
Europe, and now grows a common weed on the borders of the Mediterranean.
In Mexico, the cochineal insect was collected from the Cactus
coccinellifer long before the Spanish conquest. There are large fields
of American aloe, from which a liquor called pulque, and also an ardent
spirit, are made. The ancient Mexicans made their hemp from this plant,
and also their paper. The forests of Panama contain at least 97
different kinds of trees, which grow luxuriantly in a climate where the
torrents of rain are so favourable to vegetation, and so unfavourable to
life that the tainted air is deadly even to animals.
The sugar-cane is a native of both continents; Columbus found it wild in
many parts of America: the sweet cane is mentioned by the Prophets, and
it has grown time immemorial on the coasts of China and in the islands
of the Pacific. Its culture ranges throughout the torrid zone, and to
latitudes where the mean temperature is not under 64° of Fahrenheit. It
grows on the plains of Nepaul at an absolute elevation of 4800 feet, and
at the height of from 3500 to 5100 feet in the Cordillera of New
Grenada. It is now scarcely cultivated in the southern provinces of New
Spain, where it was introduced by the Spaniards, but it is extensively
raised in Guiana, Brazil, the West India islands, the Mauritius,
Bourbon, Bengal, Siam, Java, the Philippine islands, and China.
Maize or Indian corn is believed to have come originally from Mexico and
South America. It is an annual, requiring only summer heat; its limit is
50° N. in the American continent, and 47° N. in Europe; it ripens at an
elevation of 7600 feet in low latitudes, and in the Lower Pyrenees at
the height of 3289 feet.[165]
The flora of each West Indian island is similar to that of the continent
opposite to it. The Myrtus pimento, producing allspice, is common in the
hills; custard-apple, guava, the avocado pear, and tobacco, are
indigenous; the cabbage-palm grows to the height of 150 feet; the
palma-real of Cuba is the most majestic of that noble family; and in
Barbadoes there still exists a tree, but wearing out rapidly, which has
given the island its name.
FLORA OF TROPICAL AMERICA.
Although the flora of tropical America is better explored than that of
Asia or Africa, there must still be thousands of plants of which we have
no knowledge; and those which have come under observation are so varied
and so numerous, that it is not possible to convey an idea of the
peculiarities of this vegetation, or of the extent and richness of its
woodlands. The upper Orinoco flows for some hundred miles chiefly
through forests; and the silvas of the Amazons are six times the size of
France. In these the trees are colossal, and the vegetation so matted
together by underwood, creeping and parasitical plants, that the sun’s
rays can scarcely penetrate the dense foliage.
These extensive forests are by no means uniform; they differ on each
side of the equator, though climate and other circumstances are the
same. Venezuela, Guiana, the Amazona, and Brazil, are each the centre of
a peculiar flora. So partial is this splendid vegetation, that almost
each tributary of the great rivers has a flora of its own: particular
families of plants are so restricted in their localities, and
predominate so exclusively where they occur, that they change the
appearance of the forest. Thus, from the prevalence of the orders
Laurineæ, Sapotaceæ, and others, which have leathery, shining, and
entire leaves, the forests through which the Rio Negro, Cassiquiare, and
Tuamine flow, differ in aspect from those of the other affluents of the
Amazons. Even the grassy llanos, so uniform in appearance, have their
centres of vegetation; and only agree with the pampas of Buenos Ayres in
being covered with grass and herbs. In these tropical regions the flora
varies with the altitude also. On the Andes, almost at the limit of
vegetation, the ground is covered with purple, azure, and scarlet
gentians, drabas, alchemillas, and many other brilliantly-coloured
alpine plants. This zone is followed by thickets of coriaceous-leaved
plants, in perpetual bloom and verdure; and then come the forest-trees.
Arborescent ferns ascend to 7000 feet; the coffee-tree and palms to
5000; and neither indigo nor cocoa can be cultivated lower than 2000.
The tree yielding cocoa, of which chocolate is made, grows wild in
Guiana, Mexico, and on the coast of the Caraccas; it is now cultivated
in Central and South America, even to Chile, also in the Canary and
Philippine islands, into which it was introduced by the Spaniards. The
seeds of its fruit, which is like a cucumber, are the cocoa.
Many parts of the coasts of Venezuela and Guiana are rendered
pestilential by the effluvia of the mangrove, Avicennia, and the
manchineel, one of the Euphorbia family, consisting of 562 species in
tropical America, all having milky juice, deleterious in the greater
number. The well-known poison Ourari is prepared by the Indians of
Guiana from the fruit and bark of the Strychnos toxicaria, than which
nature has probably produced no plants more deadly. This Ourari (or
Wourali) is a creeping plant which yields the deadly juice, the powerful
effect of which was proved by Mr. Waterton’s experiments.
The Cinchona, or true bark-tree, grows only on the Cordilleras of the
Andes.[166] Some of its medicinal qualities are found in other plants of
different genera in Guiana, as the Cusparia carony, which produces the
Angostura bark. The Sapindus saponaria, or soap-tree, is used by the
natives for washing. Capsicum, vanilla, the incense-plant, the Dipteryx
odorata, whose fruit is the tonquin-bean, and the cassava or mandioc,
are natives of the country. There are two kinds of mandioc, a shrub
whose fleshy roots yield a farina eaten by the natives of Spanish
America and Brazil: the root of one is harmless, but the other contains
a poisonous milky juice, the effects of which are removed by cultivation
or pressure. It grows to about 30° on each side of the equator, and to
3200 feet above the sea-level. An acre of mandioc is said to yield as
much nourishment as six acres of wheat.
Arrow-root is native in South America; it has been transported to the
West Indies and Ceylon. The flour is the produce of the root. The plant
is said to owe its name to the belief of its being an antidote to the
poison of the arrows of the Indians. The cow-tree, almost confined to
the Cordillera of the coast of Venezuela, yields such abundance of
nutritious milky juice that it is carried in gourds, like milk from the
cow. The chocolate-plant, or cacao-shrub, fruits of the most excellent
flavour, plants yielding balsam, resin, and gum, are numerous in the
tropical regions. There the laurel tribe assume the character of
majestic trees: some are so rich in oil, that it gushes from a wound in
the bark. One of these laurels produces the essential oil which
dissolves caoutchouc, or Indian rubber, used in rendering cloth
waterproof.
Plantains of gigantic size form large forests; but palms are the most
numerous and the most beautiful of all the trees in these countries.
There are 90 species of them; and they are so local that a change takes
place every 50 miles. They are the greatest ornament of the upper
Orinoco.
The llanos of Venezuela and Guiana are covered with tall grass, mixed
with lilies and other bulbous flowers, sensitive mimosas, and palms
constantly varying in species.
No language can describe the glory of the forests of the Amazon and
Brazil, the endless variety of form, the contrasts of colour and size:
there even the largest trees bear brilliant blossoms; scarlet, purple,
blue, rose-colour, and golden yellow, are blended with every possible
shade of green. Majestic trees, as the Bombax ceiba (or silk-cotton
tree), the dark-leaved mora with its white blossoms, the fig, cashew,
and mimosa tribes, which are here of unwonted dimensions, and a thousand
other giants of the forest, are contrasted with the graceful palm, the
delicate Acacia, reeds of 100 feet high, grasses of 40, and tree-ferns
in myriads. Passifloræ and slender creepers twine round the lower
plants, while others as thick as cables climb the lofty trees, drop
again to the ground, rise anew and stretch from bough to bough, wreathed
with their own leaves and flowers, yet intermixed with the vividly
coloured blossoms of the Orchideæ. An impenetrable and everlasting
vegetation covers the ground; decay and death are concealed by the
exuberance of life; the trees are loaded with parasites while alive—they
become masses of living plants when they die.
One twenty-ninth part of the flowering plants of the Brazilian forests
are of the coffee-tribe, and the rose-coloured and yellow-flowering
bignonias are among their greatest ornaments, where all is grace and
beauty. Thousands of herbs and trees must still be undescribed where
each stream has its own vegetation. The palm-trees are the glory of the
forest: 81 species of these plants are natives of the intertropical
parts of Brazil alone; they are of all sizes, from such as have hardly
any stem to those that rise 130 feet.[167] In those parts of Brazil less
favoured by nature, the forests consist of stunted deciduous trees, and
the boundless plains have grasses, interspersed with myrtles and other
shrubs.[168]
The forests on the banks of the Paraguay and Vermejo are almost as rich
as those of the tropics. Noble trees furnish timber and fruit; the
algaroba, a kind of acacia, produces clusters of a bean, of which the
Indians make bread, and also a strong fermented liquor; the palm and
cinchona grow there; and the yerba-maté, the leaves of which are
universally used as tea in South America, and were in use before the
Spanish conquest. It is a species of holly, with leaves five or six
inches long.
The sandy deserts towards the mountains are the land of the Agave and
Cactus in all their varieties. The fibres of the Agave are made into
cordage by the Indians for fishing-nets and other uses, and the juice
affords them drink. Some larger species of Cactus give a light and
durable wood; and the Cochineal insect, which feeds on them, is a
valuable article of commerce.
Grass, clover, and European and African thistles, which have been
introduced, with a solitary Ombu at wide intervals, are the unvarying
features of the pampas; and thorny stunted bushes, characteristic of all
deserts, are the only vegetation of the Patagonian shingle. But on the
mountain valleys in the far south may be seen the winter’s bark,
arbutus, new species of beech-trees, stunted berberries, and
Misodendron, which latter is a singular kind of parasitical plant.
Large forests of Araucaria imbricata grow in the Andes of Chile and
Patagonia. This tall and handsome pine, with cones the size of a child’s
head, supplies the natives with a great part of their food. It is said
that the fruit of one large tree will maintain eighteen persons for a
year.
Nothing grows under these great forests; and when accidentally burnt
down in the mountainous parts of Patagonia, they never rise again, but
the ground they grew on is soon covered with an impenetrable brushwood
of other plants. In Chile the violently stinging Loasa appears first in
these burnt places, bushes grow afterwards, and then comes a tree-grass,
18 feet high, of which the Indians make their huts. The new vegetation
that follows the burning of primeval forests is quite unaccountable. The
ancient and undisturbed forests of Pennsylvania have no undergrowth, and
when burnt down they are succeeded by a thick growth of rhododendrons.
The southern coasts of Chile are very barren, and all plants existing
there, even the herbaceous, have a tendency to assume a hard knotty
texture. The stem of the wild potato, which is indigenous in Chile and
Peru, becomes woody and bristly as it grows old. It is a native of the
sea-strand, and is never found naturally more than 400 feet above it. In
its wild state the root is small and bitter; it is one of many instances
of the influence of cultivation in rendering unpromising plants useful
to man.
It was cultivated in America at the time of its discovery, and is so
now, at the height of from 9800 to 13,000 feet above the sea on the
Andes, and as high as 4800 feet on the Swiss Alps; it does not succeed
on the plains in hot countries, nor farther north than Iceland. It had
been introduced into Europe by the Spaniards before the time of Sir
Walter Raleigh; he brought it to England from Virginia in 1586.
Coca, the Erythroxylon Coca of botanists, is a native of the tropical
valleys on the eastern declivity of the Andes of Peru and Bolivia, where
it is extensively cultivated for its leaf, of which the tree furnishes 3
or 4 crops annually; the coca-leaf, which possesses nutritive and
narcotic qualities, is chewed by the aborigines mixed with an alcaline
substance: it allays hunger, and enables the Indian to undergo great
fatigue without any other nourishment for days together; it is an
article of great trade, and absolutely indispensable in the more
laborious profession of the miner.
Between the southern parallels of 38° and 45° Chile is covered with
extensive forests. Stately trees of many kinds, having smooth and
brightly-coloured trunks, are bound together by parasitical plants of
the monocotyledonous structure; large and elegant ferns are numerous,
and arborescent grasses entwine the trees to the height of 20 or 30
feet; palm-trees grow to the 37th parallel of latitude, their southern
limit.
Although the flora, at an elevation of 9000 feet on the Chilian Andes,
is almost identical with that of the Straits of Magellan, yet the
climate is so mild in some valleys, especially that of Antuco, that the
vegetation is semi-tropical. In it broad-leaved and bright-coloured
plants, and the most fragrant and brilliant Orchideæ, are mixed with the
usual alpine genera. Dr. Pœppig says, that whatever South Africa or New
Holland can boast of in beauty, in variety of form, or brilliancy of
colour, is rivalled by the flora in the highest zone in this part of the
Andes, even up to the region of perpetual snow; and, indeed, it bears a
strong analogy to the vegetation of both these countries.
The Andes so completely check the migration of plants, that almost
throughout their whole length there is no mingling of the floras on
their east and west sides, except at the Isthmus of Panama, where the
mahogany-tree crosses from the Atlantic to the Pacific side, and in the
same way many of the plants on the lands on the east are brought to the
west, and spread to California on one side, and as far as the dry plains
of Peru on the other.[169]
The humidity or dryness of the prevailing winds makes an immense
difference in the character of the countries on each side of the Andes.
Within the southern tropic the trade-winds come loaded with vapour from
the Atlantic, which is partly precipitated by the mountains of Brazil,
and supplies the noble forests of that country with never ceasing
moisture, while the remainder is condensed by the Andes, so that on
their eastern side there is an exuberant vegetation, while on the
western declivities and in the space which separates them from the
Pacific they are almost barren, and on the plains and in the valleys of
Peru, where rain very seldom falls, completely so, except where
artificial irrigation is employed. Even on the eastern side of these
mountains the richness of the vegetation gradually disappears with the
increasing height, till at an elevation of about 15,000 feet arborescent
plants vanish, and alpine races, of the most vivid beauty, succeed;
which, in their turn, give place to the grasses at the height of 16,138
feet. Above these, in the dreary plains of Bombon, and other lands of
the same altitude, even the thinly-scattered mosses are sickly; and at
the height of 21,878 feet the snow-lichen forms the last show of
vegetable life; confirming the observation of Don Ulloa, that the
produce of the soil is the thermometer of Peru.
ANTARCTIC FLORA.
Tierra del Fuego and Kerguelen’s Land are the northern boundary of the
antarctic lands, which are scattered round the south pole at immense
distances from one another. On these the vegetation decreases as the
latitude increases, till at length utter desolation prevails; not a
lichen covers the dreary storm-beaten rocks; and, with the exception of
a microscopic marine plant, not a sea-weed lives in the gelid waves. In
the arctic regions, on the contrary, no land has yet been discovered
that is entirely destitute of vegetable life. This remarkable difference
does not so much depend on a greater degree of cold in winter as on the
want of warmth in summer. In the high northern latitudes the power of
the summer sun is so great as to melt the pitch between the planks of
the vessels; while, in corresponding southern latitudes, Fahrenheit’s
thermometer does not rise above 14° at noon at a season corresponding to
our August. The perpetual snow comes to a much lower latitude in the
southern lands than it does in the north. Sandwich Land, in a latitude
corresponding to that of the north of Scotland, is perpetually covered
with many fathoms of snow. A single species of grass, the Aira
antarctica, is the only flowering plant in the South Shetland islands,
which are no less ice-bound; and Cockburn Island, one of that group, in
the 60th parallel, contains the last vestiges of vegetation; while the
Namesake islands, in an equally high latitude, to the north of Scotland,
are inhabited and cultivated; nay, South Georgia, in a latitude similar
to that of Yorkshire, is always clad in frozen snow, and only produces
some mosses, lichens, and wild burnet; while Iceland, 10 degrees nearer
the pole, has 870 species, more than half of which are flower-bearing.
The forest-covered islands of Tierra del Fuego are only 360 miles from
the desolate Shetland group. Such is the difference that a few degrees
of latitude can produce in these antarctic regions, combined with an
equable climate and excessive humidity. The prevalence of evergreen
plants is the most characteristic feature in the Fuegian flora. Densely
entangled forests of winter’s bark, and two species of beech-trees, grow
from the shore to a considerable height on the mountains. Of these, the
Fagus betuloides, which never loses its brownish-green leaves, prevails
almost to the exclusion of the evergreen winter’s bark and the deciduous
beech, which is very beautiful. There are dwarf species of Arbutus, the
Myrtus nummularia, which is used instead of tea, besides berberry,
currant, and fuchsia; peculiar species of Ranunculi, calceolarias,
Caryophylleæ, cruciform plants, and violets. Wild celery and
scurvy-grass are the only edible plants; and a bright yellow fungus,
which grows on the beech-trees, forms a great part of the food of the
natives. There is a greater number of plants in Tierra del Fuego, either
identical with those in Great Britain, or representatives of them, than
exists in any other country in the southern hemisphere. The sea-pink, or
thrift, the common sloewort, a primula farinosa, and at least 30 other
flowering plants, with almost all the lichens, 48 mosses, and many other
plants of the cryptogamous kinds, are identically the same; while the
number of genera common to both countries is still greater, and, though
unknown in the intermediate latitudes, reappear here. Hermite Island,
west from Cape Horn, is a forest-land, covered with winter’s bark and
the Fuegian beeches; and is the most southern spot on earth on which
arborescent vegetation is found. An alpine flora, many of the species of
European genera, grows on the mountains, succeeded higher up by mosses
and lichens. Mosses are exceedingly plentiful throughout Fuegia; but
they abound in Hermite Island more than in any other country, and are of
singular and beautiful kinds.
Although the Falkland Islands are in a lower latitude than Tierra del
Fuego, not a tree is to be seen. The Veronica elliptica, resembling a
myrtle, which is extremely rare, and confined to West Falkland, is the
only large shrub; a white-flowering plant like the aster, about four
feet high, is common; while a bramble, a crowberry, and a myrtle,
bearing no resemblance, however, to the European species, trail on the
ground, and afford edible fruit. The balsam bog, or Bolax globaria, and
grasses, form the only conspicuous feature in the botany of these
islands; and, together with rushes and Dactylis cæspitosa, or Tussack
grass, cover them, almost to the exclusion of other plants. The Bolax
grows in tufted hemispherical masses, of a yellow-green colour, and very
firm substance, often four feet high, and as many in diameter, from
whence a strong-smelling resinous substance exudes, perceptible at a
distance. This plant has umbelliferous flowers, and belongs to the
carrot order, but forms an antarctic genus quite peculiar.
The Tussack grass is the most useful and the most singular plant in this
flora. It covers all the small islands of the group, like a forest of
miniature palm-trees, and thrives best on the shores exposed to the
spray of the sea. Each tussack is an isolated plant, occupying about two
square yards of ground. It forms a hillock of matted roots, rising
straight and solitary out of the soil, often six feet high and four or
five in diameter; from the top of which it throws out a thick grassy
foliage of blades, six feet long, drooping on all sides, and forming,
with the leaves of the adjacent plants, an arch over the ground beneath,
which yields shelter to sea-lions, penguins, and petrels. Cattle are
exceedingly fond of this grass, which yields annually a much greater
supply of excellent fodder than the same extent of ground would do
either of common grass or clover. Both the Tussack-grass and the Bolax
are found, though sparingly, in Tierra del Fuego; indeed, the vegetation
of the Falkland Islands consists chiefly of the mountain plants of that
country, and of those that grow on the arid plains of Patagonia; but it
is kept close to the ground by the fierceness of the terrific gales that
sweep over these antarctic islands. Peculiar species of European genera
are found here, as a calceolaria, wood sorrel, and a yellow violet;
while the shepherd’s purse, cardamine hirsuta, and the primula farinosa,
appear to be identical with those at home. In all, there are scarcely
120 flowering plants, including grasses. Ferns and mosses are few, but
lichens are in great variety and abundance, among which many are
identical with those in Britain.
In the same hemisphere, far, far removed from the Falkland group, the
Auckland Islands lie in the boisterous ocean south of New Zealand. They
are covered with dense and all but impenetrable thickets of stunted
trees, or rather shrubs, about 20 or 30 feet high, gnarled by gales from
a stormy sea. There is nothing analogous to these shrubs in the northern
hemisphere; but the Veronica elliptica, a native of Tierra del Fuego and
New Zealand, is one of them. Fifteen species of ferns find shelter under
these trees, and their fallen trunks are covered with mosses and
lichens. Eighty flowering plants were found during the stay of the
discovery ships, of which 56 are new; and half of the whole number are
peculiar to this group and to Campbell’s Island. Some of the most
beautiful flowers grow on the mountains, others are mixed with the ferns
in the forests. A beautiful plant was discovered, like a purple aster, a
Veronica, with large spikes of ultramarine colour; a white one, with a
perfume like jessamine; a sweet-smelling alpine Hierochloe; and in some
of the valleys the fragrant and bright-yellow blossoms of a species of
asphodel were so abundant that the ground looked like a carpet of gold.
A singular plant grows on the sea-shore, having bunches of green waxy
blossoms the size of a child’s head. There are also antarctic species of
European genera, as beautiful red and white gentians, geraniums, &c. The
vegetation is characterized by an exuberance of the finer flowering
plants, and an absence of grasses and sedges; but the landscape, though
picturesque, has a sombre aspect, from the prevalence of brownish-leaved
plants of the myrtle tribe.
Campbell’s Island lies 120 miles to the south of the Auckland group, and
is much smaller, but from the more varied form of its surface it is
supposed to produce as many species of plants. During the two days the
discovery ships, under the command of Sir James Ross, remained there,
between 200 and 300 were collected, of which 66 were flowering plants,
14 of which were peculiar to the country. Many of the Auckland Island
plants were found here, yet a great change had taken place; 34 species
had disappeared and were replaced by 20 new, all peculiar to Campbell’s
Island alone, and some were found that hitherto had been supposed to
belong to Antarctic America only. In the Auckland group only one-seventh
of the plants are common to other Antarctic lands, whilst in Campbell’s
Island a fourth are natives of other longitudes in the Antarctic Ocean.
The flora of Campbell’s Island and the Auckland group is so intimately
allied to that of New Zealand, that it may be regarded as the
continuation of the latter, under an Antarctic character, though
destitute of the beech and pine trees. There is a considerable number of
Fuegian plants in the islands under consideration, though 4000 miles
distant; and whenever their flora differs in the smaller plants from
that of New Zealand, it approximates to that of Antarctic America: but
the trees and shrubs are entirely dissimilar. The relation between this
vegetation and that of the northern regions is but slight. The Auckland
group and Campbell’s Island are in a latitude corresponding to that of
England, yet only three indigenous plants of our island have been found
in them, namely, the Cardamine hirsuta, Montia, and Callitriche. This is
the utmost southern limit of tree-ferns.
Perhaps no spot in either hemisphere, at the same distance from the
pole, is more barren than Kerguelen Islands, lying in a remote part of
the south polar ocean. Only 18 species of flowering plants were found
there, which is less than the number in Melville Island, in the Arctic
Seas, and three times less than the number even in Spitzbergen. The
whole known vegetation of these islands only amounts to 150, including
sea-weeds. The Pringlea, a kind of cabbage, acceptable to those who have
been long at sea, is peculiar to the island, and grass, together with a
plant similar to the Bolax of the Falkland Islands, covers large tracts.
About 20 mosses, lichens, &c., are only found in these islands, but many
of the others are also native in the European Alps and north polar
regions. It is a very remarkable circumstance in the distribution of
plants, that there should be so much analogy between the floras of
places so far apart as Kerguelen Islands, the groups south from New
Zealand, the Falkland Islands, South Georgia, and Tierra del Fuego.
ORIGIN AND DISTRIBUTION OF CEREALIA.
The plants which the earth produces spontaneously are thus confined
within certain districts, and few of them would survive a change of
circumstances; nevertheless, Providence has endowed those most essential
to man with a greater flexibility of structure, so that the limits of
their production can be extended by culture beyond what have been
assigned to them by nature. The grasses yielding the grains are
especially favoured in this respect, though their extension depends upon
the knowledge and industry of man; no grain will be cultivated where it
can be procured from a foreign market at less expense; so that with
regard to useful plants there is an artificial as well as a natural
boundary. The cultivation of plants in gardens and hot-houses is
entirely artificial, and depends on luxury and fashion.
Tartary and Persia are presumed to have been the original countries of
wheat, rye, and oats; but these grains have been so long in use that it
is impossible to trace their origin with certainty. Barley grows
spontaneously in Tartary and Sicily, probably of different species.
Those plants which produce the grains must have had a more extended
location than any other, and they can endure the greatest extremes of
heat and cold. In high northern latitudes wheat is protected from the
inclemency of winter by sowing it in spring, or if sown in autumn a
coating of snow defends it: the polar limit is the isothermal line of
57° 2ʹ, and wheat will not form seed within less than 20° or 23° of the
equator. In America the northern limit is unknown, the country being
uninhabited; but at Cumberland House, in the very middle of the
continent, one of the stations of the Hudson’s Bay Company, in 54° N.
lat., there are fields of wheat, barley, and maize. Wheat thrives
luxuriantly in Chile and Rio de la Plata, and at elevations of 8500 and
10,000 feet above the sea. It even produces grain on the banks of the
Lake Titicaca in the Peru-Bolivian Andes at the absolute height of
12,795 feet in sheltered situations, and good crops of barley are raised
in that elevated region.
Barley bears cold better than any of the grains, yet neither it nor any
other will grow in Iceland. It is successfully cultivated in the Feroe
Islands, near Cape North, the extreme point of Norway, near Archangel on
the White Sea, and in Central Siberia to between 58° and 59° N. lat.
Rye is only cultivated where the soil is very poor, and agriculture
little understood, yet a third of the population of Europe lives on
rye-bread, chiefly inhabitants of the middle and especially of the
northern parts; its limit is about the 67th parallel of N. latitude.
Oats are scarcely known in middle and southern Europe; in the north they
are extensively cultivated to the 65th degree of N. latitude.
Rice is the food of a greater number of human beings than any other
grain; it has been cultivated from such high antiquity that all traces
of its origin are lost. It contains a greater proportion of nutritious
matter than any of the Cerealia, but, since it requires excessive
moisture, and a temperature of 73° 4ʹ at least, its cultivation is
limited to countries between the equator and the 45th parallel.
Indian corn and millet are much cultivated in Europe south of the 45th
and 47th parallels, and form an important article of food in France,
Italy, Africa, India, and America. Buck-wheat is extensively cultivated
in northern Europe and Siberia and the table-lands of central Asia; it
is a native of Asia, from whence it was brought into Europe in the 15th
century.
The cerealia afford one of the most remarkable examples of numberless
varieties arising from the seed of one species. In Ceylon alone there
are 160 varieties of rice, and at least 30 of Panicum. The endless
varieties which may be raised from the seed of one plant is most
conspicuous in the flower-garden: the rose affords above 1400; the
varieties of the pansy, calceolaria, tulip, auricula, and primrose are
without end, and often differ so much from the parent plant that it
seems almost impossible they should have had a common origin: it seems
difficult to believe that red cabbage, cauliflower, and many others,
should have sprung from the sea-kale or Brassica oleracea, so totally
dissimilar from any of them, with its bitter sea-green curly leaves.
Fashion changes so much with regard to plants that it is scarcely
possible to form even an approximation to the number known to be in
cultivation; new plants are introduced from a foreign country, and are
apt to take the place of some of the older, which are neglected and
sometimes lost; of 120,000 plants which are known to exist on the earth,
not more than 15,000 are believed to be in cultivation.
It is supposed that plants capable of bearing a great range of
temperature would exist through longer geological periods than those
more limited in their endurance of vicissitudes of temperature, and it
appears that in many instances at least the existence of varieties
depends on the life of the plant from whence they originated; the actual
duration of individuals is a subject which has not been sufficiently
studied, though the progress of physiological botany has given the means
of doing so without destroying the plant.
Since forest-trees increase by coatings from without, the growth of each
year forming a concentric circle of wood round the pith or centre of the
stem, the age of a tree may be ascertained by counting the number of
rings in a transverse section of the trunk, each ring representing a
year. Moreover, the progress of the growth is known by comparing the
breadth of the rings, which are broader in a favourable than in an
unfavourable season, though this may depend also, in some measure, on
the quality of the soil which the roots have come to in their downward
growth. If the number of concentric rings in a transverse section has
shown the age of a tree, and its girth has been ascertained by
measurement, an approximation to the age of any other tree of the same
kind still growing, under similar circumstances, maybe determined by
comparison. In this way the age of many remarkable trees has been
ascertained. The yew attains a greater age than any other tree in
Europe. According to M. De Candolle this tree increases in girth the
twelfth part of an inch in a year during the first 150 years, and rather
less in the next hundred, the increase probably decreasing
progressively. By that estimate a yew at Fountaine Abbey was reckoned by
Pennant to be 1214 years old; one at Crowhurst, in Surrey, was 1400
years old when measured by Evelyn; it has been shown by the same method
that a yew at Fotherngill, in Scotland, was between 2500 and 2800 years
old; and one at Braburn, in Kent, must have been 3000 years old: these
are the veterans of European vegetation.
The cypress rivals the yew in longevity, and may perhaps surpass it.
There is a cypress in the palace garden at Grenada which had been
celebrated in the time of the Moors, and was still known in the year
1776, as Cipres della Regina Sultana, because a sultana met with
Abencerrages under its shade. Oaks come next in order: they are supposed
to live 1500 or 1600 years. One in Welbec Lane, mentioned by Evelyn, was
computated to be 1400 years old. Chestnut-trees are known to live 900
years; lime-trees have attained 500 or 600 years in France; and birches
are supposed to be equally durable. Some of the smaller and less
conspicuous European plants perhaps rival these giants of the forest in
age: heaths, and the alpine willow, which covers the ground with its
leaves, although it is really a subterranean tree spreading to a vast
distance, are long lived. Ivy is another example of this: there is one
near Montpellier, six feet in girth, which must be 485 years old. A
lichen was watched for forty years without the appearance of change.
The antiquity of these European vegetables sinks into insignificance
when compared with the celebrated baobab, or Adansonia digitata, in
Senegal: taking as a measure the number of concentric rings counted on a
transverse incision made for the purpose in the trunk of that enormous
tree, it was proved to be 5150 years old; yet Baron Humboldt considers a
cypress in the garden of Chapultepec to be still older; it had already
reached a great age when Montezuma was on the throne of Mexico, in 1520.
These two trees are probably the most aged organized beings on the face
of the earth. Eight olive-trees on the Mount of Olives are supposed to
be 800 years old; it is at least certain that they existed prior to the
taking of Jerusalem by the Turks. There is some doubt as to the age of
the largest cedar on Lebanon; it is nine feet in diameter, and has
probably existed 800 or 900 years. There are two cedar-trees in the
Botanic Garden at Chelsea which were mentioned 600 years ago.
The age of palms and other monocotyledonous plants is ascertained by a
comparison of their height with the time which each kind takes to grow.
M. De Candolle thus estimates that the Cocos oleracea, or cabbage-palms,
may live 600 or 700 years, while the cocoa-nut palm lives from 80 to 330
years.
Mr. Babbage has made an approximation to the age of peat-mosses from the
concentric rings of the trees found in them.
MARINE VEGETATION.
A vegetable world lies hid beneath the surface of the ocean, altogether
unlike that on land, and existing under circumstances totally different
with regard to light, heat, and pressure, yet sustained by the same
means. Carbonic acid and ammonia are as essential, and metallic oxides
are as indispensable, to marine vegetation as they are to land-plants.
Sea-water contains ammonia, and something more than a twelve-thousandth
part of its weight of carbonate of lime, yet that minute portion is
sufficient to supply all the shell-fish and coral-insects in the sea
with materials for their habitations, as well as food for vegetation.
Marine plants are more expert chemists than we are, for the water of the
ocean contains rather less than a millionth part of its weight of
iodine, which they collect in quantities impossible for us to obtain
otherwise than from their ashes.
Sea-weeds fix their roots to anything—to stone, wood, and to other
sea-weeds: they must, therefore, derive all their nourishment from the
water, and the air it contains; and the vital force or chemical energy
by which they decompose and assimilate the substances fit for their
maintenance is the sun’s light.
Marine plants, which are very numerous, consist of two groups—a jointed
kind, which include the Confervæ, or plants having a thread-like form;
and a jointless kind, to which belong dulse, laver, the kinds used for
making kelp, vegetable glue, iodine, that in the Indian Archipelago, of
which the sea-swallows make their edible nests, and all the gigantic
species which grow in submarine forests, or float like green meadows in
the open sea. Flower-bearing sea-weeds are very limited in their range,
which depends upon the depth of water and the nature of the coasts; but
the cryptogamic kinds are widely dispersed, some species are even found
in every climate from pole to pole. No doubt the polar currents at the
surface, and the stratum of uniform temperature lower down, are the
highways by which these cosmopolites travel.[170]
There are fewer vegetable provinces in the seas than on land, because
the temperature is more uniform, and the dispersion of the plants is not
so much interfered with by the various causes which disturb it on
land.[171]
Marine vegetation varies both horizontally and vertically with the
depth, and it seems to be a general law throughout the ocean that the
light of the sun and vegetation end together; it consequently depends on
the power of the sun and the transparency of the water; so different
kinds of sea-weeds affect different depths, where the weight of the
water, the quantity of light and heat, suit them best. One great marine
zone lies between the high and low water marks, and varies in species
with the nature of the coasts, but exhibits similar phenomena throughout
the northern hemisphere. In the British seas, where, with two
exceptions, the whole flora is cryptogamic,[172] this zone does not
extend deeper than 30 fathoms, but is divided into two distinct
provinces, one to the south and another to the north. The former
includes the southern and eastern coasts of England, the southern and
western coasts of Ireland, and both the channels; while the northern
flora is confined to the Scottish seas and the adjacent coasts of
England and Ireland. The second British zone begins at low-water mark,
and extends below it to a depth from 7 to 15 fathoms. It contains the
great tangle sea-weeds, growing in miniature forests, mixed with fuci,
and is the abode of a host of animals. A coral-like sea-weed is the last
plant of this zone, and the lowest in these seas, where it does not
extend below the depth of 60 fathoms, but in the Mediterranean it is
found at 70 or 80 fathoms, and is the lowest plant in that sea. The same
law prevails in the Bay of Biscay, where one set of sea-weeds is never
found lower than 20 feet below the surface; another only in the zone
between the depths of 5 and 30 feet; and another between 15 and 35 feet.
In these two last zones they are most numerous; at a greater depth the
kinds continue to vary, but their numbers decrease. The seeds of each
kind float at the depth most genial to the future plant; they must
therefore be of different weights. The distribution in the Egean Sea was
found by Professor E. Forbes to be perfectly similar, only that the
vegetation is different, and extends to a greater depth in the
Mediterranean than in more northern seas.[173] He also observed that
sea-weeds growing near the surface are more limited in their
distribution than those that grow lower down, and that with regard to
vegetation depth corresponds with latitude, as height does on land.
Thus, the flora at great depths, in warm seas, is represented by kindred
forms in higher latitudes. There is every reason to believe that the
same laws of distribution prevail throughout the ocean and every sea.
Sea-weeds adhere firmly to the rocks before their fructification, but
they are easily detached afterwards, which accounts for some of the vast
fields of floating weeds; but others, of gigantic size and wide
distribution, are supposed to grow unattached in the water itself. There
are permanent bands of sea-weed in our British Channel and in the North
Sea, of the kind called Fucus Filum, which grow abundantly on the
western coasts of the Channel, and they lie in the direction of the
currents, in beds 15 or 20 miles long, and not more than 600 feet wide.
These bands must oscillate with the tides between two corresponding
zones of rest, one at the turn of the flood, and the other at the turn
of the ebb. It is doubtful whether the Fucus natans or Sargassum
bacciferum grows on rocks at the bottom of the Atlantic, between the
parallels of 40° north and south of the equator, and, when detached, is
drifted uniformly to particular spots which never vary, or whether it is
propagated and grows in the water; but the mass of that plant, west of
the Azores, occupies an area equal to that of France, and has not
changed its place since the time of Columbus. Fields of the same kind
cover the sea at the Bahama Islands and other places, and two new
species of it were discovered in the Antarctic seas.
The Macrocystis pyrifera and the Laminaria radiata are the most
remarkable of marine plants for their gigantic size and the extent of
their range. They were met with on the Antarctic coasts two degrees
nearer the south pole than any other vegetable production, forming, with
one remarkable exception, the utmost limit of vegetable life in the
south polar seas. The Macrocystis pyrifera exists in vast detached
masses, like green meadows, in every latitude from the south polar ocean
to the 45th degree N. lat. in the Atlantic, and to the shores of
California in the Pacific, where there are fields of it so impenetrable,
that it has saved vessels driven by the heavy swell towards that shore
from shipwreck. It is never seen where the temperature of the water is
at the freezing point, and is the largest of the vegetable tribe, being
occasionally 300 or 400 feet long. The Laminaria abounds off the Cape of
Good Hope and in the Antarctic Ocean. These two species form great part
of a band of sea-weed that girds Kerguelen Islands so densely, that a
boat can scarcely be pulled through it; and they are found in great
abundance on the coasts of the Falkland group, and also in vast fields
in the open sea, hundreds of miles from any land: had it ever grown on
the distant shores, it must have taken ages to travel so far, drifted by
the wind, currents, and the sand of the seas. The red, green, and purple
lavers of Great Britain are found on the coasts of the Falkland Islands;
and, though some of the northern weeds are not found in the intervening
warm seas, they reappear here. The Lessonia is the most remarkable
marine plant in this group of islands. Its stems, much thicker than a
man’s leg, and from 8 to 10 feet long, fix themselves by clasping fibres
to the rocks beyond the high-water mark. Many branches shoot upwards
from these stems, from which long leaves droop into the water like
willows. There are immense submarine forests off Patagonia and Tierra
del Fuego, attached to the rocks at the bottom. These plants are so
strong and buoyant, that they bring up large masses of stone; and, as
they grow slanting, and stretch along the surface of the sea, they are
sometimes 300 feet long. The quantity of living creatures which inhabit
these marine forests and the parasitical weeds attached to them is
inconceivable, they absolutely teem with life. Of the species of marine
plants which are strictly antarctic, including those in the seas of Van
Diemen’s Land and New Zealand, Dr. Hooker has identified one-fifth with
the British Algæ.
The high latitudes of the Antarctic Ocean are not so destitute of
vegetation as was at first believed. Most minute objects, altogether
invisible to the naked eye, except in mass, and which were taken for
siliceous shelled animalcules of the infusoria kind, prove to be
vegetable. They are a species of the Diatomaceæ, which, from their
multitudes, give the sea a pale ochreous brown colour. They increase in
numbers with the latitude, up to the highest point yet attained by man,
and, no doubt, afford the supply of food to many of the minute animals
in the antarctic seas. Genera and species of this plant exist in every
sea from Victoria Land to Spitzbergen. It is one of the remarkable
instances of a great end being effected by small means; for the death of
this antarctic vegetation is forming a submarine bank between the 76th
and 78th parallels of south latitude, and from the 165th to the 160th
western meridian.
Great patches of Confervæ are occasionally met with in the high seas.
Bands several miles long, of a reddish-brown species, like chopped hay,
occur off Bahia, on the coast of Brazil; the same plant is said to have
given the name to the Red Sea; and different species are common in the
Australian seas.