IUCN threat status:

Not evaluated

Comprehensive Description

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Description

This introduced plant is a winter or summer annual with prostrate or ascending stems up to 2½' long. These stems are light green or reddish green and densely covered with white hairs (although older stems become less hairy); they branch occasionally. The alternate compound leaves are trifoliate. Young trifoliate leaves toward the tips of the stems have short hairy petioles, while older trifoliate leaves have longer petioles. At the base of each petiole, there is a pair of stipules that are lanceolate to ovate and variable in size. The leaflets of the compound leaves are up to 2/3" long and about half as much across; they are medium to dark green, obovate or oval-ovate, hairy or nearly hairless, and slightly dentate along their margins. Each middle leaflet has a short stalk, while the lateral leaflets are sessile. The upper surface of each leaflet has fine lateral veins that are light green and straight. Occasionally, individual flowerheads are produced from the axils of the trifoliate leaves on peduncles up to 3" long. Each flowerhead is about ¼" across and globoid in shape; it consists of a dense cluster of 15-50 yellow flowers. Each flower is about 1/8" long; when fully open, it has a pea-like floral structure with an upper standard and lower keel; the former is relatively larger than the latter in size. The base of each flower consists of a small green calyx with 5 narrow teeth. The blooming period occurs from late spring to early fall and can last several months. Each flowerhead is replaced by a dense cluster of seedpods. Each seedpod is dark-colored, hairy, strongly curled, and about 1/8" long; it contains a single dark seed that is somewhat flattened and reniform (kidney-shaped). The root system consists of a coarse branching taproot that can form nodules.

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Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© John Hilty

Source: Illinois Wildflowers

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