Page:An introduction to physiological and systematical botany (1st edition).djvu/174

 144 nature as furnishing food to the brute creation, are subjects foreign to our present purpose, and need not here be insisted upon. Their essential importance to the plant which bears them, and the curious functions by which they contribute to its health and increase, will presently be detailed at length. We shall first explain their different situations, insertions, forms, and surfaces, which are of the greatest possible use in systematical botany.

The leaves are wanting in many plants, called for that reason plantæ aphyllæ as Salicornia, Engl. Bot. t. 415 and 1691, Stapelia variegata, Curt. Mag. t. 26, glanduliflora, Exot. Bot. t. 71, and all the species of that genus. In such cases the surface of the stem must perform all their necessary functions.

1. With respect to Situation and Position,

Folia radicalia, radical leaves, are such as spring from the root, like those of the Cowslip, ''Engl. Bot. t. 5, and Anemone Pulsatilla, t.'' 51.

Caulina, stem-leaves, grow on the stem