Page:An introduction to physiological and systematical botany (1st edition).djvu/127

Mr. Knight denominates it the germen, but that term is appropriated to a very different part, the rudiment of the fruit. The expanding Embryo, resembling a little feather, has been for that reason named by Linnæus Plumula; it soon becomes a tuft of young leaves, with which the young stem, if there be any, ascends. Till the leaves unfold, and sometimes after, the cotyledons, assuming their green colour, perform their functions; then the latter generally wither. This may be seen in the Radish, Lupine, Garden Bean, and various umbelliferous plants, in all which the expanded cotyledons are remarkably different from the true leaves. Such is the general course of vegetation in plants furnished with two cotyledons, or dicotyledones; but I have already mentioned a very distinct tribe called monocotyledones, having but one. These are the Grass and Corn tribe, Palms, the beautiful Orchis family, and many others. In these the cotyledon, or body of the seed, does not ascend out of the ground, and some have considered them as having no cotyledon at all. See Mr. Salisbury's paper in the Transactions of the Linnean Society, v. 7,