120 



COLLEGE BOTANY 



and that most of the reserve food is stored around the embryo 

 instead of in the cotyledons. The seeds of the beet, tomato> 

 pepper, buckwheat and many of our common weeds belong to this 

 type, but owing to their small size are not so satisfactorj' 

 for study. 



Germination of the Castor-Oil Seed. — This process is very 

 similar to that of the bean, but the cotyledons are covered for 



Fig. 85. — Seed of castor-oil plant; (a) and {b) upper and lower surfaces: (c) after removal of the 

 seed coat: (d, e) cotyledon showing leaf characters. 



some time by the endosperm, which they gradually absorb. As 

 the endosperm disappears, the cotyledons become green and more 

 leaf -like and frequently persist for a long time. 



Therefore, the cotyledons sen^e first for the absorption of 

 stored food and later as foliage. 



The Corn Type. — This is a monocotyledonousi type in which 

 the food is stored in the endosperm. It is not a simple seed, but 

 a true caryopsis fruit (page 112) in which the ovary coats have 

 united with the seed coats. Therefore, it is not strictly com- 

 parable to the seeds of the bean and castor-oil bean. It is 

 flattened and somewhat wedge-shaped, the edges rounded and the 

 large end smooth or indented. On one side is a groove within 

 which the embryo is clearly visible. If we cut the grain longi- 

 tudinally, we find the parts as follows: the radicle or primary 



