36 



BIOLOGY FOR BEGINNERS 



FIELD CORN KtRNEL 



food that they do not come above ground as do most beans. They 

 remain below and never approach the appearance of leaves. 



However, having so much stored food, the plumule of the pea 

 does not need to develop early, so is very small, and even when 

 growth commences, the first leaves of the plumule are mere scales, 

 and do not have much ability to get food. The true leaves do not 



make their appearance till the food in 

 the cotyledons becomes scant. 



Corn. External Structure. The corn 

 seed, as it is usually called, is really a 

 fruit corresponding to the bean pod, 

 rather than to the bean itself. One seed 

 completely fills the fruit, so that the 

 seed coats and fruit coats cannot be 

 distinguished. 



As a result of this fact, the hilum 

 and micropyle are covered by the fruit 

 coats and what might be mistaken for 

 the hilum is really the point of attach- 

 ment of the corn fruit (grain) to the cob. 

 On one side of each grain can be seen a 

 light-colored, oval area, which marks the 

 location of the embryo, visible beneath 

 the coats. On the same side, but at the 

 FIG. 6. External and in- end opposite the point of attachment, is 

 ternal structure of corn seed, located a tiny point, the silk scar, 



where the corn " silk " formerly grew. 



Corn. Internal Structure. Internally the corn consists of a 

 large endosperm, containing much starch, proteid, and some oil, 

 and at one side near the point of the grain, a much smaller part, 

 the embryo. 



This embryo has but one cotyledon, a rather irregular, oval 

 structure, wrapped around the plumule and hypocotyl, and lying 

 in close contact with the endosperm. Its function is to digest and 

 transmit the food stored in the endosperm to the growing seedling. 

 It is a real digestive organ, which secretes, ferments, and makes 



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