Time of bloom: June to September.
Seed-time: July to October.
Range: Atlantic States from Massachusetts to Florida; along the Great Lakes from Quebec to Minnesota, and southward through the Mississippi Valley to the Gulf of Mexico and Texas.
Usually this plant is prostrate, trailing or twining to a length of three to eight feet, branching at the base, and with leaves at somewhat distant intervals; but occasionally it will have a stouter, more leafy stalk, held erect and less than two feet tall; in either form rough, with downward-pointing hairs. The plants are said to be very nutritious and are much liked by grazing cattle, but in cultivated fields they are often rather troublesome.
Leaves pinnately trifoliolate with slender petioles and very small, narrow, pointed stipules; leaflets one to three inches in length, rather long ovate, the lateral ones often obtusely lobed on the outer sides and the terminal one on both sides, or the upper leaves may have entire leaflets and the lower ones be distinctly three-lobed. Flowers axillary, lifted on long, slender peduncles in dense capitate clusters of three to ten pale purple blossoms, fading to a greenish color, the keels curved and slender, the standards rounded and about a half-inch wide. Pods round, slender, sessile, nearly smooth, tipped with the persistent bent style, four- to eight-seeded, the beans downy. (Fig. 179.)
Fig. 179. - Trailing Wild Bean (Strophostyles helvola). X 1/3.
Prevent seed production by hoe-cutting while small. Dormant seeds often germinate and bloom late, after horse cultivation of crops has ceased. Follow the cultivated crop with heavy seeding to clover or cowpeas.