CHAPTER NIX 
ORIGIN OF THE CULTIVATED LEGUMES 
Clover - Alfalfa. The lentil. The bean- The pea. The vetch- The lupine - 
The soy bean - The cowpea 
A certain class of valuable plants is known as legumes. The 
distinguishing botanical trait of legumes is that they bear their 
seeds in pods, like peas and beans. The pod may be large and 
straight as in these familiar species, small and inconspicuous as 
in clover, or spiral-shaped as in alfalfa. In all cases, however, 
the seeds, whether large or small, resemble beans in splitting 
readily into two equal parts, unlike corn or wheat or the seeds 
of the grasses generally. 
The physiological distinction of leguminous plants is a very 
peculiar one, and one that is unknown in plants outside this 
particular family. It is this: there will nearly always be found 
growing on the roots of all legumes little nodules or warts called 
tubercles. These tubercles vary in size and shape from those 
of the red clover, which are not so large as the head of a 
pin, up to those of the soy bean, which are as large as a 
small pea. 
These tubercles are really the home of millions of microscopic 
plants called bacteria, which are parasitic upon the legume ; that 
is to say, they depend upon the host plant for food, and to 
that extent they are a disadvantage. This disadvantage is, how- 
ever, more than offset by their exceeding usefulness in the 
matter of fertility. 
The agricultural distinction of the legumes generally is that 
the bacteria within these tubercles have the power of taking the 
free nitrogen of the air and putting it into combinations that 
may be used as food for plants generally, a property that is not 
257 
