GARDENING.-NO. 4 . 
176 
to the above proposed exhibition of fleeces. He 
says the exhibition of two or three fleeces would be 
no test of the quality of a flock, that he cannot re¬ 
serve a large number of fleeces for comparison, but 
that he would willingly allow Mr. B. to compare 30 
or 40 samples of his Rambouillet wool with an 
equal number from his (Mr. R.’s) flock, the weight 
of washed fleece being attached to each such sam¬ 
ple, at the nest N. Y. State Fair. 
GARDENING.—No. 4. 
Geographical Distribution of Vegetables. —This 
branch of the study of horticulture points out the 
grand features of the immense extent which plants 
occupy, from the regions of perpetual snow to the 
bottom of the ocean, and to the interior of the 
globe. The superior limits of vegetation are 
known, but not the inferior; for everywhere in 
the bowels of the earth are germs which develope 
themselves when they find a space and nourish¬ 
ment suitable for vegetation. 
The territorial limits to vegetation are determined 
in general by three different causes; by sandy 
deserts, which seeds cannot pass over either by 
means of winds or birds; by seas too vast for the 
seeds of plants to be drifted from one shore to the 
other ; and by long and lofty chains of mountains. 
To these causes are to be attributed the fact, that 
similar climates and soils do not always produce 
similar plants. Thus, in some parts of North 
America, which resemble Europe in respect to soil, 
climate, and elevation, not a single European plant 
is to be found in a natural state. The potato, first 
found by the Spaniards on the Western continent, 
does not grow naturally in like situations on the 
Eastern. There is scarcely a single plant found in 
Africa that grows wild in South America, and the 
splendid dahlia of Mexico was never found upon 
the steppes of Asia. 
Physical Distribution of Vegetables. —The natural 
circumstances affecting the distribution of plants, 
are temperature, elevation, moisture, soil, and 
light. Some plants belong to mountains, some to 
valleys, and others to plains. Every species of 
soil has vegetables peculiarly adapted to it. Some 
plants are confined to water, and some to moist re¬ 
gions, while others grow only in dry tracts, or on 
the surface of naked rocks. Some require the hot¬ 
test climate, and some a climate that is temperate, 
while others will thrive only in the midst of frost 
and snow. In this way, nearly the whole surface 
of the earth is covered with vegetation, and plants 
are found even in the dark vaults of caverns, and 
in the beds of the sea. Some plants will flourish 
with a high degree of heat, for a short time, 
although it is followed by severe cold; others re¬ 
quire only a moderate degree of warmth, longer 
continued, and are adapted to elevated regions. 
Many plants will flourish where trees will not, 
and some approach the region of perpetual snow. 
Those regions where no other vegetable will grow, 
are provided with the hardy lichen (capable of sup¬ 
porting men and animals), which is found beneath 
the snow in the depth of winter. 
Temperature has the most obvious influence on 
vegetation. In this respect, not only the medium 
temperature of a country ought to be studied, but 
the temperature of different seasons of that country. 
In advancing north from the polar circle, the birch, 
which*bears the severity of the cold best, dwindles- 
in size, till at last it ceases to grow at 70°, the 
point where man gives up the cultivation of grain. 
North of this, shrubs, bushes, and herbaceous 
plants only are to be met with. Wild thyme, 
creeping willow, and brambles, cover the face of 
the rocks, and the arctic cloud-berry here assumes 
its most delicious flavor and perfume. Shrubs 
next disappear, and their place is supplied by the 
saxifrage, primrose, and the low-flowering herbs 
and grasses; then comes the lichen, which covers 
vast tracts of country, and beyond this we find 
only a naked, sterile soil, and perpetual snows. 
On the borders of the temperate zones the ever¬ 
greens commence. The potato, cabbage, turnip, 
and similar garden vegetables, may be cultivated, 
and cranberries, whortleberries, and currants, are 
the only fruits. In the northern parts of these 
zones, the apple, pear, and fruits of the cold regions 
are produced in perfection; but in the southern 
parts these fruits often lose their finest flavor, and 
in some instances degenerate entirely, near the 
borders of the hot or torrid zone. Here the wine- 
grape, peach, almond, and apricot flourish; here 
we first meet with the olive and the fig, and in 
Europe, the orange and lemon, and as we proceed 
towards the tropics, we find the sugar-cane, coffee, 
and date. The orange, lemon, citron and fig, are 
here of the most delicious flavor, and still nearer to 
the equator the various species of palm characterize 
these regions. Some of the trees of the torrid 
zone attain a size, of which a native of northern 
countries can scarcely conceive. The mighty 
baobab, on the plains of the Senegal in Africa, is 
found with a trunk 50,. 60, and even 70 feet in cir¬ 
cumference, and one of the leaves of the fan-palm 
is often of sufficient size to cover ten or a 
dozen men. 
Elevation, or the height of the soil above the 
level of the sea, affects climate much in the same 
manner as latitude ; while, at the same time, it 
occasions a material difference in atmospheric 
pressure. This diminished pressure is one of the 
causes of the diminutive size of plants, grown in 
elevated regions. Experiments have been made to 
prove this, by causing seeds of barley to germinate 
in soil placed in vessels under different degrees of 
atmospheric pressure ; and the result has been, that 
where the pressure was greatest, the vigor of the 
plant was greatest also. In ascending the moun¬ 
tains of the torrid zone, as the elevation varies, 
each section has its own distinct plants, and we 
find in succession the productions of every region 
from the equator to the poles. 
Moisture, or mode of watering, natural to vege 
tables, is a circumstance which has a powerful in¬ 
fluence on the facility with which plants grow in 
any given soil. The qualities of water, or the na¬ 
ture of the substances dissolved in it, must neces¬ 
sarily influence powerfully the possibility of certain 
plants growing in certain places. But the differ¬ 
ence in this respect is much less than would be 
imagined, because the food of one species of plant 
differs very little from that of another. The most 
remarkable case is that of salt-marshes, in which 
a great many vegetables will not live, whilst a 
