The seeds are large, but the embryo is very small. A section of a nearly ripe seed shows the embryo (_em._) occupying the upper part of the embryo sac which does not nearly fill the seed and contains no endosperm. The bulk of the seed is derived from the tissue of the body of the ovule, which in most seeds becomes entirely obliterated by the growth of the embryo sac. The cells of this tissue become filled with starch, and serve the same purpose as the endosperm of other seeds. This tissue is called "perisperm." Of food plants belonging to this order, the banana (_Musa_) is much the most important. Others of more or less value are species of arrowroot (_Maranta_) and ginger (_Zingiber_). There are three families: I. _Musaceæ_ (banana family); II. _Zingiberaceæ_ (ginger family); and III. _Cannaceæ_ (_Canna_, _Maranta_). ORDER VI.--_Gynandræ_. By far the greater number of the plants of this order belong to the orchis family (_Orchideæ_), the second family of the order (_Apostasieæ_), being a small one and unrepresented in the United States. The orchids are in some respects the most highly specialized of all flowers, and exhibit wonderful variety in the shape and color of the flowers, which are often of extraordinary beauty, and show special contrivances for cross-fertilization that are without parallel among flowering plants. [Illustration: FIG. 89.--_Gynandræ_. _A_, inflorescence of the showy orchis (_Orchis spectabilis_), × 1 (_Orchideæ_). _B_, a single flower, with the upper leaves of the perianth turned back to show the column (_x_). _sp._ the spur attached to the lower petal or lip. _o_, the ovary, × 1. _C_, the column seen from in front. _an._ the stamen. _gy._ the stigmatic surface, × 1. _D_, the two pollen masses attached to a straw, which was inserted into the flower, by means of the viscid disc (_d_): i, the masses immediately after their withdrawal; ii, iii, the same a few minutes later, showing the change in position. _E_, diagram of the flower; the position of the missing stamens indicated by small circles.]