Page:An introduction to physiological and systematical botany (1st edition).djvu/51

 Rh The leaf of the White Willow is clothed with a line silky or satiny cuticle.

The cuticle of the Betony, and of many other plants, is extended into rigid hairs or bristles, which in the Nettle are perforated and contain a venomous fluid.

On the fruit of the Plum, and on many leaves, we find a blueish dry powder covering the cuticle, which is a resinous exudation, and it is difficult to wet the surface of these plants. Rain trickles over them in large drops.

In the Cork tree, the Common Maple, and even the Dutch Elm, the cuticle is covered with a fungous substance most extraordinary in its nature, though familiar to us as cork.

In grasses and some other plants the ingenious Mr. Davy has found a flinty substance in the cuticle.

What seems to be the cuticle on the trunk of the Plane, the Fir, and a kind of Willow called Salix triandra, rather consists of scales of bark, which having performed their functions and become dead matter, are rejected by the increasing bark beneath them; and this accords with M. Mirbel's idea of