386 ELEMENTARY STUDIES IN BOTANY 



can obtain their own nitrates with the help of soil bacteria ; 

 but this does not mean that they can do well on poor soil. 



Peas. The cultivation of peas is extremely old, the plant 

 being a native of southern Europe and Asia, and used exten- 

 sively by the most ancient races. There are numerous 

 varieties of garden peas and field peas, but there are two 

 types of garden peas that can be recognized easily : (1) those 

 with smooth seeds, which are earlier and hardier varieties; 

 and (2) those with wrinkled seeds, which are of better quality. 

 Many of the garden varieties need poles six to eight feet 

 high ; others are not such high climbers ; while still others are 

 dwarfs and do not need stakes. The method of planting and 

 cultivating is the same as for beans, and will be described in 

 the next paragraph. 



Beans. There are many kinds of beans, but the ordinary 

 beans cultivated in this country are probably natives of trop- 

 ical America. The two types in ordinary cultivation are the 

 bush beans, which are field beans, and the pole beans, which 

 are garden beans, the latter demanding more fertile soil than 

 the former, especially the best of all the pole beans, the Lima 

 bean. In the cultivation of field beans, the seeds are usually 

 planted in rows two to three feet apart, with the plants three 

 to six inches apart in each row, and the soil is kept well stirred 

 between the rows. In the case of pole beans, the poles are 

 set about four feet apart each way and four or five beans 

 planted around each pole, and the soil is cultivated frequently. 



Sweet corn is also a notable seed-vegetable, which has been 

 presented in connection with the cereals (p. 350). 



