There is, however, some variation in the development of the
various parts of plants belonging to the same species, that is
caused by differences of soil, climate, and other conditions. In
identifying plants beginners must, therefore, distinguish between
essential and accidental variations (cf. Tumbe, page 106). The
following extract from Sir Jos. Hooker gives the chief causes of
such variations :—

“A bright light and open situation, particularly at consider-
able elevations, without too much wet or drought, tends to
increase the size and heighten the colour of flowers in proportion
to the stature and foliage of the plant. Shade, on the contrary,
especially with rich soil and sufticient moisture, tends to increase
the foliage and draw up the stem, but to diminish the number,
size, and colour of the flowers. A hot climate and dry situation
tend to increase the hairs, prickles, and other productions of the
epidermis, and to shorten and stiffen the branches. Moisture in
a rich soil has the contrary effect. The neighbourhood of the
sea, or a saline soil or atmosphere, imparts a thicker and more
succulent consistence to the foliage and almost every part of the
plant, and appears not unfrequently to enable plants, usually
annual, to live through the winter.
«The luxuriance of plants growing in a rich soil, and the
dwarf, stunted character of those crowded in poor soils, or in
the cold, damp regions of high mountain-tops, is well known.”


278 APPENDIX’


2. Genera.— We have seen that the Banyan tree (Ficus
bengalensis) constitutes a species. If we muster the vegetable
kingdom, we can easily find other trees which resemble the
Banyan tree in most important points of structure, such as the —
Peepul tree or the Country Fig tree. Such plants form one
genus, viz., the genus « Ficus”.
