Page:An introduction to physiological and systematical botany (1st edition).djvu/249

 Rh It is commonly situated at the base of the latter, in pairs, and is extremely different in shape in different plants.

The most natural and usual situation of the Stipulas is in pairs, one stipula on each side of the base of the footstalk, as in Lathyrus latifolius, Engl. Bot. t. 1108, whose stipulas are half arrow-shaped; also in Willows, as Salix stipularis, t. 1214, and S. aurita, t. 1487. In Rosa, Potentilla, and many genera allied to them, the stipulas are united laterally to the footstalk. See Potentilla alba, t. 1384. In all these cases they are extrafoliaceæ, external with respect to the leaf or footstalk; in others they are intrafoliaceæ, internal, and are then generally simple, as those of Polygonum, t. 1382, 756, &c. In a large natural order, called Rubiaceæ, these internal stipulas in some cases embrace the stem in an undivided tube above the insertion of the footstalks, like those of Polygonum just mentioned; in others, as the Coffee, Coffea arabica, and the Hamellia patens, Exot. Bot. t. 24, they are separate leaves between the footstalks, but meeting