456 



BOTANY OF CROP PLANTS 



There are between 15 and 20 species of Soja, natives of 

 tropical Asia, Africa, and Australia. There is only one 

 species of any economic importance. This is Soja max. 



SOJA MAX (Soy Bean, Soja Bean, Coflfee Bean) 



Description. — This is an erect, bushy appearing, hairy 

 annual, varying from i3^ to 6 feet in height (Fig. 192). Unlike 

 the cowpea, it has a definite growth, that is, reaches a cer- 

 tain size and matures its seed. All the pods of the soy bean 



mature at one time. In the 

 cowpea, new pods are formed 

 as long as the plant lives. 

 The tap root is short and 

 strong. The leaves are tri- 

 foliate. Usually they have 

 withered and fallen by the 

 time the pods are mature, 

 but in some varieties remain 

 green and stay on the plant 

 for sometime after the pods 

 mature. The flowers are 

 borne in axillary clusters; 

 they are small, and either 

 white or purple in color. 

 The flowers are seK-pollinated 

 as a rule, and are completely 

 self-fertile. Occasional cross-fertiUzation occurs in the field 

 when varieties are planted very close together. The pods 

 are from i to 23^ inches long, yellowish or brown, and 

 covered with short bristly hairs. As many as 300 to 400 

 pods have been found on one plant, and each pod usually 

 contains two or three seeds. In fact, the soy bean is the 

 greatest seed producer of any legume grown in temperate 



Fig. 192. — Soy bean (Soja max). 

 {After Piper.) 



