‘NITROGEN-GATHERING 173 
will not produce a large crop of any leguminous 
plant unless well supplied with phosphoric acid 
and potash. Therefore, in attempts to increase the 
protein supply of the farm by means of leguminous 
plants, it is quite as necessary to fertilize with the 
minerals as it would be to grow any other crop. 
This is entirely reasonable, as the mineral constit- 
uents cannot be secured from any other source 
than the soil and these are quite as essential to 
leguminous crops as to any others, or as the nitro- 
gen itself. 
Kinds of leguminous crops 
The family Leguminose, or pulse family, is 
very large and it is represented in the flora of all 
parts of the globe. Some of the legumes are trees, 
as locusts, red-bud, yellow-wood; others are 
bushes, as furze, broom, lead-plant; some are 
tall woody climbers, as wistaria; others are agri- 
cultural herbs, some of which are grown for for- 
age, as alfalfa, clovers, cowpea, soybean, velvet- 
bean, vetches, pea, and these are to be considered 
further in the three chapters that follow. 
