262 



TYPICAL FLOWERING PLANTS 



Figure 255. — Diagram 

 of Corn Seed. 



201. Corn -'Seed.'' — A grain or kernel of corn, com- 

 monly called a seed, is like a bean (1) in containing a 

 young plant, the corn embryo ; (2) in containing food 

 for the use of the embryo when it first begins to grow ; 



and (3) in having marks upon it. 

 On the top of the kernel is a slight 

 prominence, the scar which marks the 

 place where one thread of the so- 

 called silk was attached. On one 

 side of the kernel is a depression 

 beneath which the embryo lies, and 

 at the base is a stalk by which the 

 kernel is attached to the cob during 

 its development (Figure 255). 



A corn grain differs from a bean in 

 being a fruit, — that is, the seed case 

 adheres to the seed coat as a second 

 covering. A kernel of corn, therefore, corresponds to a bean 

 pod containing but one seed. Corn differs from the bean 

 also in the position of the embryo, which is at one side of the 

 food supply. The 

 latter is called the 

 endosperm (en' do- 

 sperm : Greek, endo, 

 within ; sperma, a 

 seed). Another dif- 

 ference between the 

 two is that the corn 



has a single modified cotyledon called the scutellum (sku- 

 tel'lum : Latin, diminutive of scutum, a shield), the 

 use of which is to absorb and digest the food and carry 

 it to the embryo (Figure 255). The cotyledon of the 

 corn never appears above ground. The corn embryo has 

 its leaves rolled into a tight, pointed bud, which enables 



Figure 256. — Sun- 

 flower " Seed." 



A fruit. 



Figure 257. — ■ 

 Squash Seed. 



