242 



BOTANY. 



Fig. 137.— Germination of In- 

 dian Corn. J, II, III. succes- 

 sive stages. AB.xid.B. front and 

 side views of a separated em- 

 bryo; w, root; e, part or seed 

 filled with endosperm; sc. co- 

 tyledon; r, its open margins; 

 6, b',h", leaves of voung plant ; 

 I. fragment of wall of ovary. 



Natural size- 



leaves is for the most part such that 

 the veins run more or less parallel 

 to one another, and when they 

 join each other enclose four-sided 

 spaces; rarely, however, their veins 

 are irregularly distrihuted and 

 form an irregular network. 



512. The germination of Mono- 

 cotyledons may be illiistrated by 

 the Indian corn. Here the embryo 

 lies partly imbedded in one side of 

 the large endosperm (Fig. 136). 

 The first leaf of the young plant 

 (the cotyledon, or scutellum), sc, 

 has its broad dorsal surface in con- 

 tact with the endosperm; anteriorly 

 it is curved entirely around the re- 

 mainder of the embryo. 



513. Under proper conditions 

 the main root pushes through the 

 root -sheath {ws, Figs. 136, 137). 

 The plumule, consisting of a mi- 

 nute stem and a few rudimentary 

 leaves, next pushes out through 

 the upper end of the curved co- 

 tyledon {II, Fig. 137). The co- 

 tyledon remains in contact with 

 the endosperm and absorbs nour- 

 ishment from it for the sustenance 

 of the growing parts. Lateral 

 roots soon appear upon the main 

 root, and adveptitious pqes ari^e 



