Kummerowia Schindl. Contributed by Jay A. Raveill

Plants annual. Stems spreading to ascending or less commonly erect, with many well-developed branches, sparsely to densely hairy. Leaves alternate, short- to long-petiolate. Stipules persistent, ovate to narrowly ovate, herbaceous and green when young, becoming papery and straw-colored at maturity, the margins entire, inconspicuously and minutely appressed-hairy, the surfaces glabrous or nearly so, the venation prominent. Leaf blades appearing palmately trifoliate (the middle leaflet sometimes slightly longer than the lateral pair), the leaflets without stipels. Leaflets sessile or nearly so, obovate, narrowly elliptic, or narrowly oblong, usually rounded to shallowly notched at the tip, often with a minute hairlike extension of the midvein, the margins entire, hairy, the upper surface glabrous, the undersurface sparsely to moderately pubescent with relatively stiff hairs along the midvein, pinnately veined. Inflorescences axillary at most upper and some lower nodes, appearing as solitary flowers or small clusters of 2–5 flowers, each subtended by 3 or 4 minute papery bracts. Calyces 5-lobed but appearing 4-lobed because of the nearly complete fusion of the uppermost 2 sepals, the lobes similar in length, glabrous or hairy, usually prominently nerved, persistent and papery at fruiting. Corollas papilionaceous, pink to purplish pink (drying bluish purple) with large white patches at the base of the banner, the keel longer than the wings. Stamens 10, 9 of these with the filaments fused together most of their length, the remaining filament free, the anthers all of similar size. Fruits 1-seeded, indehiscent, flattened, the rim angled and somewhat thickened, the surface moderately pubescent with minute appressed hairs. Seeds 1.5–2.0 mm long, somewhat flattened, the surface smooth, brown to black, shiny. Two species, native to eastern Asia, widely introduced in North America.

The acceptance of Kummerowia as a genus distinct from Lespedeza is not universal. Kummerowia differs from Lespedeza primarily in its annual habit (vs. perennial or shrubby), conspicuous papery stipules, and details of the highly reduced inflorescence (Akiyama and Ohba, 1985; Nemoto and Ohashi, 1993). As in some Lespedeza, both species of Kummerowia can produce cleistogamous flowers.

Both species in the genus have been planted widely in the eastern United States for forage and soil improvement (Isely, 1948), and less commonly as an annual hay crop. They establish readily and thrive even in areas of thin and poor soils, but can out-compete native vegetation in such areas as sandstone glades. Kummerowia striata was introduced to the United States from Japan in 1846, but the later-introduced K. stipulacea (in 1919) has replaced it in importance in Missouri, both as an agricultural plant and as an escape (Steyermark, 1963).