The integuments grow with the embryo sac, and become brown and hard, forming the shell of the seed. The stalk of the ovule also enlarges, and finally forms the peculiar, spongy appendage of the seeds already noticed ([Fig. 81], J, K).
CHAPTER XVI.
CLASSIFICATION OF THE MONOCOTYLEDONS.
In the following chapter no attempt will be made to give an exhaustive account of the characteristics of each division of the monocotyledons, but only such of the most important ones as may serve to supplement our study of the special one already examined. The classification here, and this is the case throughout the spermaphytes, is based mainly upon the characters of the flowers and fruits.
The classification adopted here is that of the German botanist Eichler, and seems to the author to accord better with our present knowledge of the relationships of the groups than do the systems that are more general in this country. According to Eichler’s classification, the monocotyledons may be divided into seven groups; viz., I. Liliifloræ; II. Enantioblastæ; III. Spadicifloræ; IV. Glumaceæ; V. Scitamineæ; VI. Gynandræ; VII. Helobiæ.
Order I.—Liliifloræ.
The plants of this group agree in their general structure with the adder’s-tongue, which is a thoroughly typical representative of the group; but nevertheless, there is much variation among them in the details of structure. While most of them are herbaceous forms (dying down to the ground each year), a few, among which may be mentioned the yuccas (“bear grass,” “Spanish bayonet”) of our southern states, develop a creeping or upright woody stem, increasing in size from year to year. The herbaceous forms send up their stems yearly from underground bulbs, tubers, e.g. Trillium ([Fig. 83], A), or thickened, creeping stems, or root stocks (rhizomes). Good examples of the last are the Solomon’s-seal ([Fig. 83], B), Medeola (C, D), and iris ([Fig. 84] A). One family, the yams (Dioscoreæ), of which we have one common native species, the wild yam (Dioscorea villosa), have broad, netted-veined leaves and are twining plants, while another somewhat similar family (Smilaceæ) climb by means of tendrils at the bases of the leaves. Of the latter the “cat-brier” or “green-brier” is a familiar representative.
Fig. 83.—Types of Liliifloræ. A, Trillium, × ¼. B, single flower of Solomon’s-seal (Polygonatum), × 1. C, upper part of a plant. D, underground stem (rhizome) of Indian cucumber root (Medeola), × ½. E, a rush (Juncus), × 1. F, a single flower, × 2. A–D, Liliaceæ; E, Juncaceæ.