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DescriptionThis native wildflower is a trailing or climbing annual vine about 3-9' long that branches occasionally. The slender stems are light green, gray-green, or dull red, terete, and hairy; they can climb by twining around the stems or branches of neighboring plants. Alternate trifoliate leaves occur at intervals along the stems. The leaflets are 1-2" long and ½1¼" across; the terminal leaflet is usually a little larger than the lateral leaflets. The leaflets are broadly lanceolate to ovate with well-rounded bases and smooth margins; the terminal leaflet has a short stalk at its base (petiolule), while the lateral leaflets are nearly sessile. For this variety of Strophostyles helvula, the leaflets lack obtuse basal lobes, unlike the typical variety. The upper leaflet surfaces are medium green and hairless (or nearly so), while their lowers surfaces are pale green and hairless (or nearly so). The slender petioles of the trifoliate leaves are about 1-2" long; they are usually slightly pubescent. At the base of each petiole, there is a pair of tiny linear-lanceolate stipules. At the axils of some leaves, there develops individual stalks (peduncles) of flowers; these stalks are 3-6" long. At the apex of each stalk, there is a dense cluster of 3-10 nearly sessile flowers; usually only 1-2 flowers are in bloom at the same time. Each flower is about 1/3" long or a little more, its petals consisting of a large rounded banner, a pair of slender lateral petals, and a narrow keel that is curled upward. These petals are light pink to pink, fading to white or pale green; at the bottom of the banner, there is a small patch of yellow. At the base of each flower, there is a short tubular calyx with 5 teeth; this calyx is sparsely hairy. At the base of each calyx, there are lanceolate tiny bracts with pointed tips that are about the same length as the calyx. The blooming period occurs from mid-summer to early fall and lasts about 2 months. Each fertile flower is replaced by a cylindrical seedpod that is 23½" long at maturity. The seedpod is initially green, but later becomes dark brown; it is nearly glabrous to sparsely hairy. Individual seeds are about ¼" long, oblongoid in shape, and pubescent. Each seedpod eventually divides into two parts to disperse the seeds.