196 BOTANY OF CROP PLANTS 



moved enough to shake pollen out. Cross-pollination is also 

 very common. Individual flowers do not, as a rule, remain 

 open longer than the evening of the day they open. The 

 brown and withered stamens and stigmas commonly protrude 

 from between the closed glumes. 



The different types of sorghum cross readily. 



Fruit. — The mature grain may be entirely or in part en- 

 closed by .the ' ' glumes . " It is ova 1 , a little longer than broad , 

 smooth, and tipped with the remains of two style branches. 

 The position of the embryo is seen at the base of the grain on 

 one of the fiat surfaces. The point of attachment — an oval, 

 brown area — is found at the base of the grain on the other 

 flat surface. 



The seed is flattened in the durras, pyriform in some of the 

 sorgos, and globular in kafir, kowliang, and shallu. 



In some types of sorghum, the pericarp bears starch. The 

 aleurone layer consists of one row of small cells. The starchy 

 endosperm is mealy within and more or less horny without. 



Varieties. — The sorghums are divided into two main di- 

 visions: (i) saccharine or sweet sorghums, and (2) non-sac- 

 charine sorghums. Saccharine sorghums are tall, leafy, and 

 have an abundance of sweet juice, and a light crop of seed. 

 The chief varieties are Amber, Orange, and Sumac. Non- 

 saccharine sorghums are more stocky, as a rule, contain less 

 Juice, and have a heavy crop of seed. Non-saccharine 

 sorghums are divided into three groups; (i) kafir group, in- 

 cluding those with erect, long cylindrical heads full of 

 obovate seeds (kafirs, white milo, etc.); (2) durra group, 

 including those with thick, compact, ovate, pendant inflo- 

 rescences, and large, flattened seeds (yellow milo, durra, 

 feterita) ; and (3) broom corn group, in which the heads are 

 loose and spreading. Frequently the heads are on recurved 

 stems, called "goose necks." 



