MEADOW PLANTS 41 
45. Alfalfa (Medicago sativa L.) is the most important 
forage crop in the United States. In the irrigated regions 
of the West it is almost the only forage plant grown and 
is there used for both hay and pasture. Alfalfa was intro- 
duced from Europe by the Spaniards and attained 
importance in our western states simultaneously with 
irrigation. Its use spread eastward in the arid and semi- 
arid regions until it reached the borders of the timothy 
region. Within recent years this crop has been success- 
fully introduced in many parts of the East and South. It 
does not thrive on an acid soil, hence the necessity of using 
lime in many parts of the East in preparing the land for 
alfalfa. Where a good stand is obtained, a permanent 
meadow is formed, yielding cuttings every four to six 
weeks during the growing season, two or three cuttings 
in the more northern regions, as many as ten in the hot 
southern valleys of California. The meadow lasts indefi- 
nitely, but sooner or later suffers from the incursions of 
various weeds and must be broken up and reseeded. As 
alfalfa is not a grass, it will not be further discussed here, 
but the student is referred for detailed information to 
Farmers’ Bulletin No. 339 from the United States Depart- 
ment of Agriculture. 
46. The clovers are legumes belonging to the genus 
Trifolium. Certain allied plants are also known as clover 
but with a modifying term, such as bur clover (Medicago 
arabica Huds.), sweet clover (Melilotus alba Desv.), Japan 
clover (Lespedeza striata (Thunb.) Hook. & Arn.), all 
belonging to the family Leguminosz. The true clovers 
include the common red clover (Trifolium pratense L.), 
which is usually referred to merely as clover, alsike (7. 
hybridum L.), white clover (7. repens L.), and crimson 
clover (7. incarnatum L.). The first two are used for 
