Page:An introduction to physiological and systematical botany (1st edition).djvu/257

 Rh, having each a bag of poison at its base, like the fang of a serpent; as well as in numerous plants whose hairy coats exude a viscid moisture. But the hairs which clothe many plants are merely a protection against cold, heat, or insects. Sometimes they are hooked, sometimes branched and entangled, as in Mullein, Verbascum, t. 549, &c. In Croton, Sulanum, and Lavatera they have often a starry figure. Very generally they are found, under a microscope, to be curiously jointed. Some Begoniæ bear on their leaves flat little straps called by authors ramenta, shavings, instead of cylindrical hairs; but I know not that they at all differ in nature from the usual pubescence, nor do they merit to be particularly distinguished. Some of the natural order of asperifoliæ, as Echium, t. 181, and Lycopsis, t. 938, especially some exotic species of this order, are clothed with curious white hard tubercles from which their bristles proceed. Echium pyrenaicum, ''Desfont. Atlant. v.'' 1. 164, is an instance of this.