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ern Pole than these are to the opposite one. Iceland for instance, in lat. 62° N., proverbially barren as it is,
and upon which no tree, but a few stunted birches, is to be found, contains certainly five times as many flowering
plants as Lord Auckland’s group and Campbell’s Island together, whose rich vegetation is evident on their
being first approached from sea ; and yet the numerical proportion which the two great groups of flowering
plants bear to one another in each country is almost identical. Kerguelen’s Land is on the southern limit of
vegetation in its own longitude, as we may presume from its containing only eighteen species of flowering
plants ; but these cover as much of the surface of the island as the plants of Spitzbergen do, and yet the latter
country contains forty-five species, though on the verge of Arctic vegetation and infinitely nearer the Pole.
Lastly, on Walden Island (la t. 80^° N.) we have the last traces of phænogamic plants in the northern hemisphere,
and in the opposite one beyond the South Shetlands (63° S.) no flowering plants exist; but whilst the
former islet boasts of ten species of flowering plants, the latter contains but a solitary grass.
The uniformity of the Flora at the different levels in any given island of the South is to be expected from
the paucity of species, and we further find that these are spread over vast extents of country. This is remarkably
the case with the southern American Flora, where the northern limit at which the antarctic Beech grows
near the sea is 45°, from which latitude as far as 56° S. the level of the ocean seems to be its natural habitat :
again, the plants which form the bogs of the Cbonos Archipelago in lat. 45° S. ore the same as those of Cape
Horn, and the general features of the vegetation of the two localities are the same. In the northern temperate
regions a very different state of things will be found to prevail : compare the Flora of the south of France, in
the latitude of the Chonos Archipelago, with that of Argyleshire in the parallel of Cape Horn, and how little
similarity exists ; and this not only because tbe plants of France cannot bear the climate of Scotland, but because
new forms are developed in the latter country, equally unsuited to the south of France. Many parallel
cases to this might be adduced, all tending to prove th a t there are conditions in tbe physical geography of the
southern islands which render them unfavourable to the production of species, but which are accompanied with a
luxuriant development of such as do exist : and further, that species which form the mass of the vegetation
under these conditions are such as continue to be typical of tbe Flora through many degrees of latitude whose
mean temperature is considerably different.
The equable climate which these countries now under consideration enjoy, is doubtless mainly attributable
to the vast body of ocean surrounding them ; and though the want of new species must in a measure depend
on the limited extent of surface for their development, it is not altogether from the want of space that the paucity
of new forms in proceeding to the South is to be accounted for, since in no other part of the globe can
sixteen degrees of so luxuriant a Flora composed of so few species be traversed.
All parts of antarctic America as it is called, a name its ungenial climate alone, and not its geographical
position, warrants, are wet, foggy and cold ; snow-storms and gales of wind prevail throughout the year ; and not
only on the hills, for the atmosphere seems so loaded with moisture, that a precipitation on the upper regions
is generally followed a t once by rain or snow on the lower grounds. In tbe summer the sun scarcely exerts
any power without raising mists which intercept its rays. The difference between the summer and winter temperature
is small, and the diurnal changes trifling. The perennial hurricanes which sweep the exposed surfaces
of the hills seem alone materially to check the vegetation, for even on the mountains the plants of the plains
reappear wherever a shelter is afforded. In no part of Scotland does 1700 feet of elevation exist without showing
a material change in the vegetable kingdom, such a height producing many subalpine and even alpine
plants not met with at the level of the ocean ; but though in Hermite Island the mountains attain that height,
there is scarcely a plant growing upon them which does not equally exist in the open grounds near the sea.
Nor is there probably any country where the prevailing species, forming the mass of the Flora, have such wide
ranges as in Antarctic America.
From this we may presume, that plants will pass through many degrees of latitude, and consequently from
one climate to another, provided there is no sudden change of temperature to check their pro g ress* ; th a t is to
say, if in eack climate the difference between the extremes is the same, small, and that change slow ; and that
we may expect the range of individual species to increase with the uniformity of the temperature throughout
the year.
The above observations have been drawn chiefly from a consideration of the antarctic American Flora,
which is the only one sufficiently investigated hitherto for this purpose. The plants of the Middle Island of
New Zealand are only known from the collections of Banks and Solander, Forster and Menzies, which were
made in Queen Charlotte's Sound and Dusky Bay, chiefly in the la tte r; those of the Southern or Stewart’s
Island are entirely unknown; the Northern Island maybe considered as pretty well explored, h u t an aggregate
of the whole shows the Flora of New Zealand to be in all probability the poorest of any country of its size
situated in the same latitude. Though this group extends from lat. 34“ to the 48th degree, the summers of the
northern extremity are not scorching, nor the winters, in its southern, severe. It is true th a t its high mountains
have been but partially explored ; but botanists have ascended them, as Mr. Bidwill, Dr. Dieffenbach, and
Mr. Colenso, in whose collections the amount of new forms from so considerable an altitude as th a t of 6 -1 0 ,0 0 0
feet is very trifling, and tbe species brought by each person the same. In the immediate neighbourhood of Port
Jackson, 400 species of flowering plants may be easily collected in four days’ excursions; in the same time
scarcely half that number would be detected in the Bay of Islands, very little to the southward of Sydney in
latitude; and on extending the journeys further in each country to thirty or forty miles, the disproportion increases.
A remarkable uniformity in the Flora pervades all the South Sea Islands, also accompanied with a
singularly equable temperature. The change which an elevation of 10,000 feet produces in the Flora of Colombia
is complete, and the number of species inhabiting the plains of Quito much exceeds that in the low forests
of the west coast of America, in the same parallel; but though the volcanic islands of the Sandwich group
attain a greater elevation than this, there is no such development of new species at the upper level.
Amongst the many branches of inquiry into which the science of Botanical Geography divides itself, that
which concerns the comparative richness in species of countries similarly situated is a highly interesting one. An
exuberant vegetation we And not to be necessarily the index of an extensive flora, nor is it in the most densely
clothed spots th a t the greatest variety of forms is to he met with, b u t very often tbe contrary. ^ Few lands we
have seen are so deceptive in this respect as New Zealand and Tierra del Fuego; and on extending the inquiry,
we further see th a t the sandy plains of Australia, the Cape of Good Hope, and the campos of central Brazil, are
richer in species than the more luxuriant woods of those or most other countries.
P late XLIV. & XLV. Fig. 1, a male flower ; fig. 2, p e ta l; fig. 3, stamen ; fig. 4, poUen ; fig. 6. imperfect
ovarium of male flower ; / p . 6, female flower with pedicel and b ra c te a ; fig. 7, ovarium from d o .; fig. 8, ovule ;
fig. 9, immature capsule ; fig. 10, longitudinal, a n d /p . 11, transverse section of d o .; fig. 12, ripe capsule, the
valves burst open ; fig. 13, side, and fig. 14. front view of a seed ; fig. 13, transverse section of do., showing the
outer membrane ; fig. 16, albumen coated with the inner membrane removed from the outer ; fig. 17, embryo :
—all magnified.
* A familiar instance of the advantage of slow changes of temperature in enabling plants to endure trans-
portation, is found in the application of Mr. Ward’s glazed cases for transmitting plants to England through
different climates. One of the main features of his philosophical contrivance is, th a t their construction induces a
slow change of temperature in the atmosphere immediately surrounding the plants, and prevents their suffering
from any sudden valuations.
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