Kummerowia is a small genus of two annual herbaceous legumes in the family Fabaceae (subfamily Faboideae), native to eastern Asia. The genus was segregated from the much larger genus Lespedeza and is sometimes still encountered under that name in older literature; the two species, K. striata (Japanese bushclover or Japanese clover) and K. stipulacea (Korean bushclover or Korean clover), were both formerly known as Lespedeza striata and Lespedeza stipulacea, respectively.
Plants in this genus are slender, low-growing annuals reaching roughly 15–40 cm in height, with alternate, trifoliolate leaves bearing oval leaflets. Flowers are small, pea-like, and appear in pink, purple, or white in axillary clusters of one to three. A distinctive biological feature is the production of two flower types: chasmogamous flowers that open and allow cross-pollination by insects, and cleistogamous flowers that remain closed and self-fertilize, ensuring seed set even when pollinators are absent. The fruit is a small, dry, indehiscent legume pod containing a single seed. The two species can be told apart by the extent of calyx coverage over the pod: in K. stipulacea the calyx covers one-third to one-half of the pod; in K. striata it covers one-half to four-fifths.
The native range of the genus extends across eastern Asia from the Russian Far East through China, Korea, and Japan south to Vietnam and Laos. Both species have been introduced outside their native range — particularly K. striata, which became widely naturalized in the eastern United States following introduction in the mid-nineteenth century, where it was planted intentionally for pasture, erosion control, and land reclamation on disturbed and mine-damaged soils. As nitrogen-fixing legumes, Kummerowia species improve soil fertility by converting atmospheric nitrogen into plant-available forms. They are also ecologically significant as forage for deer and livestock and as seed sources for songbirds and gamebirds.
Etymology
The genus name Kummerowia honours Johann Kummerow (1784–1857), a German physician and naturalist. The common names "Japanese bushclover" and "Korean bushclover" reflect the primary native ranges of each species within the genus. The species were long placed in Lespedeza and are still known under those names in much historical and agricultural literature.
Distribution
Kummerowia is native to eastern Asia, with its range extending from the Russian Far East through China, Korea, and Japan south to Vietnam and Laos. K. striata has become naturalized in the eastern United States — documented from New York to Florida and west to New Mexico — following intentional and accidental introductions beginning in the 1840s.
Ecology
Both species favour open, disturbed habitats including fields, roadsides, and forest margins. K. striata grows best in moist, sandy, well-drained soils in full sun across a pH range of 4.5–7.0 (optimal 6.0–6.5). The plants are pollinated primarily by bees and also host caterpillars, beetles, and moths; seeds are consumed by songbirds, gamebirds, and small mammals such as the Prairie Deer Mouse; deer browse the foliage. As legumes, both species fix atmospheric nitrogen through root-nodule symbiosis, enriching the soils in which they grow.
Cultural Uses
Kummerowia striata has a long history of use in traditional Chinese medicine, where the whole plant is used as an anti-inflammatory to promote blood circulation, clear heat, and detoxify; traditional indications include dysentery, sores, fever, headache, and diarrhea. Agriculturally, both species have been used as pasture plants and hay crops, for green-manure nitrogen enrichment (paired with bunch grasses), for erosion control, and for revegetation of coal-mine spoil banks and other severely disturbed lands. The leaves and seeds of K. striata are also edible to humans when cooked, and seeds can be ground into meal for baking.
Taxonomy Notes
Kummerowia was separated from Lespedeza on the basis of morphological characters including the indehiscent single-seeded pod and the presence of cleistogamous flowers. The two species remain the only accepted members of the genus, and GBIF records the genus as containing exactly two descendants. Older botanical and agricultural literature frequently retains the Lespedeza names (L. striata, L. stipulacea).
