GERMINATION OF BEAN 



L67 



and they assume grotesque forms. Fig. 284. Try this 

 with peas aud beans. 



312. The first internode above the cotyledons be- 

 tween the cotyledons and the plumule is 

 the epicotyl. It elevates the plumule into the 

 air, and the plumule- leaves expand into tin , 



first trui leaves of the '^"" l ^- 

 plant. These first true leaves, however, 

 may be very unlike the later leaves. 



313. GERMINATION OF BEAN. The 



common bean, as we have seen (Fig. 



282) has cotyledons which occupy all 



the space inside the seed-coats. When 



"V"'~ the hypocotyl <>r elongating caulicle 



^ emerges, the plumule- leaves have begun 



288 I termination of cas- 

 tor bean. Endosperm to enlarge and to 



unfold (Fig. 285). 



The hypocotyl elongates rapidly. One 



end of it is held by the roots. The 



other is held by the seed-coats in the 



soil. It, therefore, takes the form of 



,-i loop, and its central pari "comes 



up" firsl (a, Pig. 286). Presently 



it draws the cotyledons oul of the 



seed-coats, and then it straightens 



and the cotyledons expand. These 



cotyledons or "halves of the bean," 



persisl for some time, (6, Pig. 286). 

 They often become green and probably 

 perform Mime function of foliage. Be- 

 cause of its large Bize, Lima bean shows 



all these partS Well. 



31 I. GERMINATION OF CASTOR BEAN. 



,,,,,, in the castor bean the hilum and 

 ,,::,;:;;"" -"'' micropyle are at the smaller end (Fig. 



90 I terminal Ion rouiplete 

 in castor l - : l 1 1 



