PAET I 



CHAPTEE I 



THE SEED AND ITS GERMINATION 



The seed. A seed is a miniature plant, 

 or embryo, with some accessory parts, in a 

 resting or dormant state, and capable under 

 suitable conditions of reproducing the kind 

 of plant which bore it. 



The power of producing seeds is peculiar 

 to the higher plants (seed plants, or sper- 

 matophytes) and sharply distinguishes them 

 from all lower forms of plant life. 



The embryo may nearly or quite fill the 

 interior of the seed, as in Fig. 1, or it may 

 constitute only a small part of the bulk of 

 the latter, as in Figs. 3, 4. 



2. Form and position of the embryo. 

 The embryo shows great diversity of form; 

 it may have one, two, or several seed leaves. 



FIG. 1. Lengthwise sec- 

 tion of a squash seed 



c, hypocotyl; co, cotyle- 

 01' cotyledons (FlgS. I, 3, 12). These may don; e, endosperm; h, 



be straight, as in the squash seed, or much hilum; p w plun ??. le j 



' t, testa. Magnified 



curved and folded, as in the seed of the 

 four-o'clock, morning-glory, or buckwheat, 

 but they are almost always closely packed for economy of space 



5 



t, testa. 



about two and a half 

 times 



