WHAT 18 A SEED? 93 



119a. The internode lying above the point of attachment of 

 the cotyledons between the cotyledons and the plumule is called 

 the epicotyl; that below the cotyledons is the hypocotyl. The 

 hypocotyl was formerly called the radicle, upon the supposition 

 that it is an incipient root; but it is a stem (except, perhaps, 

 the very tip), and the root develops from its end. 



120. The embryos of the squash and bean oc- 

 cupy the whole interior of the seed, and the 

 nutriment which sustains the sprouting 

 plantlet is stored in the cotyledons. In 

 the onion it is not so. Fig. 92 is a 



FIG. 92. . e 



section of an onion seed. The monocoty- 



Sectionof . 



seed, ledonous embryo is coiled up in a mass 

 of starchy matter; and a similar condition 

 is seen in the buckwheat (Fig. 93). 

 Nutritive material stored outside the em- 

 bryo is called the endosperm. 



FIG. 93. 120a. The endosperm varies greatly in quantity and 



Section of in physical and chemical character. In many plants, as 



buckwheat the cereal grains, it affords most of the material which 



seed. is utilized for human food. In the cocoa-nut only a part 



of the liquid matter solidifies into endosperm, leaving 



the "milk" in the center; the embryo is comparatively very small, 



and can be found, of course, near the micropyle. 



12 1 A seed, then, is a body which is the 

 direct product of a flower and a result of a 

 sexual process, and which contains a miniature 

 plant or embryo; and its office is to produce a 

 new plant. In nearly all cases the embryo is 



