Family: Fabaceae, Pea view all from this family
Description This erect to prostrate, freely branched plant bears thin spikes of yellow pea-like flowers and bright green, trifoliate leaves, both somewhat fragrant.
Habit: introduced annual, biennial or perennial herb.
Height: 1.5-7 ft (0.5-2 m)
Leaf: alternate, trifoliate, short-stalked; 3 small leaflets, oblong to ovate, 0.5-1 in (1-2.5 cm) long, 0.25 in (6 mm) wide, edges completely toothed.
Flower: small, yellow drying to cream, somewhat drooping, 0.3 in (8 mm) long; in long-stalked spike, 1-6 in (3-15 cm) tall, held both terminally and in leaf axil.
Fruit: small pod, oval, beaked, ridged or wrinkled, 0.15 in (4 mm) long, black to dark grey; with 1-2 seeds.
Flower April to September, 2 or 3 weeks before white sweet clover.
Habitat A wide variety of open, sunny sites with neutral to alkaline soil: disturbed sites, roadsides, railways, fields, riparian zones, streambanks, prairies, mountain shrub communities, floodplains, fens, cottonwood bottomlands, sagebrush, sand dunes, meadows, grasslands; ponderosa pine, rocky mountain juniper, and pionyon-juniper communities; to 5000 ft (1500 m).
Range Native to central Eurasia, introduced from Europe in the mid-1700s as a crop or for bee keeping; escaped and naturalized in every U.S. state and every Canadian province except Nunavut; widely cultivated for honey production, forage, reclamation, erosion control, green manure, and as the source of the blood thinner Coumadin.
Discussion Also called yellow melilot, ribbed melilot, common melilot, cornilla real. Considered weedy or invasive in some areas.
Some botanists treat white sweet clover as synonomous with yellow sweet clover, M. officinalis. Although yellow and white sweetclover are more alike than different, the following differences are common:
- White sweetclover is generally taller, more erect, with coarser stems and branches than yellow sweetclover;
- White sweetclover racemes are much longer than those of yellow sweetclover;
- White sweetclover leaflets are often less than half as wide as yellow sweetclover leaflets;
- White sweetclover pods are veined, while yellow sweetclover pods are wrinkled.