374 



A TEXTBOOK OF BOTANY [Cn. VIII, 2 



time in suspension. It has always a small unjointed stem, 

 the HYPOCOTYL, which bears at one end the foimrlfl f f,jfln for. 

 a root, at tne other the foundation for a bud, and close 



16 tn latter oM or more "seed leaves?' 



"or COTYLEDONS (-b'igs. ^67-tfJ. These 

 cotyledons, which vary from leaf-thin to 

 hemispherically thick, are oftenest two, 

 less frequently one, and sometimes 

 several, as prevails in the Pine family. 

 While the cotyledons are commonly 

 viewed as morphologically leaves, modi- 

 fied by their peculiar position and func- 



FIG. 267. Embryo J . 



of Lima Bean, as it tions, there is doubt as to whether they 

 appears without the rea iiy originated as leaves, or are the 



seed coat, and on re- . , . , 



moval of one cotyle- descendants of special organs by which 

 don; x. The largest em bryos originally absorbed food direct 



part is cotyledon. J mr i_ j u 



from the parent plants. The bud be- 

 tween the cotyledons is mostly undeveloped in the seed, 

 but in some large, well-developed embryos, it produces visible 

 leaves, in whinh nfl.sft i| f ]s called the PLUMULE (Fig. 267). 



Second in importance is the nutritive FOOD, which is sup- 

 plied by the parent plant, and consists chiefly of starch, oils, 

 and proteins, in a dry and concentrated condition. In some 

 Kinds tnis lood occurs in a special tissue, 

 called ENDOSPERM, surrounding the em- 

 bryo, which therefore lies embedded 

 within it (the so-called ALBUMINOUS 

 seeds, Fig. 270) ; but in others the food 

 is contained inside the embryo itself, .?J G - 2 . 68 - Embr >? 



* 01 Morning (jrlory, with 



mostly in the cotyledons which are then one cotyledon removed; 

 conspicuously enlarged ; and the embryo 



X 2. There is no 

 plumule. 



now completely fills the space within the 



seed coats (EX-ALBUMINOUS seeds, Fig. 271). The_endosperm 



originates in the embryo sac simultaneously with the embryo, 



(.page cJ54J, and the two develop step by step together until 

 they fill the embryo sac, f and even (through the absorption 



