500 
COLLECTIONS AND RECOLLECTIONS. 
latter soil, as its fragments diminish in size, conduct us by degrees 
to the following class : 
8. Plants g f Sands, or very barren soil, in the classification of 
which much difficulty is experienced : thus, plants of the sand of the 
sea shore are confounded with saline plants; those of barren soil, 
with the species of cultivated land, and those of coarse sand are not 
different from those of gravel. v 
9. Plants of sterile places, that are very compact, as stiff clayey 
soils, or such as have their surface hardened by drought or heat, or 
those which are trodden hard by man or animals. 
10. Pla7its which follow Man. These are few in number, and 
more fixed in their station, either in consequence of nitrous salts 
being necessary to their existence ; or because, perhaps, azotised 
matter is requisite for their nutriment. 
11. Forest Plants, among which are to be distinguished the trees 
that form the forest, and the herbs which grow beneath their shade. 
The latter are to be seperated into two kinds : those which can sup¬ 
port a considerable degree of shade during all the year, which are 
found in evergreen woods; or such as require light in the winter, 
like those which are found among deciduous trees. 
V2. Bushes and Hedge Plants. The shrubs which compose this 
division differ from the plants of the forests in their smaller size, and 
bv the thinness of their leaves. The herbaceous kinds that grow 
among them are ordinarily climbing plants. 
13. Subterranean Plants, which live either in dark caverns, as the 
Byssus ; or within the bosom of the earth, as the Truffle. These can 
dispense altogether with light, and several cannot even endure it. 
Plants that grow in the hollows of old trees have great analogy with 
those of caverns. 
14. Mountain Plants, as subdivisions of which all the other 
stations may be taken. We generally class among mountain plants 
such as, in Europe, are not found lower than five hundred yards ; 
but this is quite an arbitrary limit. The most important division is 
between those which grow on mountains, the summit of which is 
covered with eternal snow, and those of mountains which lose their 
crest of snow in summer. In the former, the supply of water is not 
only continual, but more abundant and colder, as the heats of sum¬ 
mer advance; in the latter, on the contrary, the supply of water 
ceases when it becomes most requisite. The former are evidently 
much more robust than the latter. 
15. Parasitical Plants; that is to say, such as are either desti¬ 
tute of the power of pumping up their nourishment from the soil, or 
