An Illustrated Guide to ARIZONA WEEDS
The University of Arizona Press
ANNUAL YELLOW SWEETCLOVER, sour clover
ANNUAL YELLOW SWEETCLOVER-Melilotus indicus (L.) All.
DESCRIPTION-Annual or sometimes a biennial which reproduces only by seeds. The main stem is erect, with many spreading branches from above the base, 1 1/2 to 3 feet high. The leaves are alternate, and divided into 3 leaflets as in bur clover, but are much larger. They are 1/2 to 1 1/4 inches long, toothed above the middle with the tip indented or blunt, and a reddish bar along the midrib.
The yellow flowers are pealike, and less than 1/8 inch long. They are numerous and spikelike along the upper half of slender flower stalks, which are 2 to 4 inches long and arise from the upper leaf axils. The flower buds are erect, but soon bend downward. The small globeshaped pods are swollen on one edge, wrinkled, about 1/12 inch long, and contain 1 or 2 seeds. The seed is eggshaped, about 1/16 inch long, dark greenish brown, with a honeycombed and roughened surface.
DISTRIBUTION-Annual yellow sweetclover, introduced from Eurasia, is often a pest in lawns. It is found throughout the state in damp soil on bottomlands, gardens, roadsides, fields, ditches, and waste places. Often this weed is a serious problem in croplands, as small grains, citrus orchards, and winter vegetables; frequently a nuisance in alfalfa hay, but not often in alfalfa seed; 100 to 7,500 feet elevation; flowering November to June.
Copyright (c) 1972 The Arizona Board of Regents