SOME USEFUL PLANTS 825 
certain grasses known as cereals, and on account of this 
and other facts the Grass family is the most important 
family of plants from the economic point of view. Wheat 
is the most highly prized of the grains on account of 
its high food value, digestibility, and fitness for bread- 
making. The United States is the leading wheat- and 
corn-growing country, producing more than one-fourth of 
the world’s crop of the former grain and four-fifths of 
the latter. 
Rice is extensively grown in South Carolina and the 
Gulf States, but the world’s principal.supply comes from 
Asia. It differs from the other cereals in requiring to be 
cultivated on land that can be flooded during part of the 
year. For this reason rice culture is often attended by 
malaria. 
405. Leguminous Seeds. — The Pea family (Leguminosae) 
comprises about seven thousand species, and many seeds 
which form a considerable part of human food are derived 
from this family. The ones most generally used in our 
own country are peas and beans. Whether eaten in an 
unripe condition or after becoming mature and dry, they 
form a highly valuable source of proteid food. Peanuts 
are the seeds of a leguminous plant largely grown in the 
South Atlantic States and elsewhere. Our crop of these 
is largely consumed at home, but also forms a consider- 
able article of export. Other leguminous seeds much used 
as articles of food in Europe and elsewhere, although not 
as yet largely consumed in the United States, are broad 
beans or Windsor beans, chick peas, and lentils. 
406. Other Seeds. — A great number of seeds which do 
not come from plants of the Grass family or the Pea fam- 
ily are used as human food. The most important tropical 
