Herbs annual, 10–60 cm, gla­brous or glabrescent. Stems usu­ally erect or ascending, rarely prostrate, branched. Leaves palmate; stipules triangular-lanceolate, 0.4–0.8 cm, margins entire, apex dark purple or reddish, sharply recurved, subulate; petiole 0.5–10 cm; petiolules 0.5 mm; leaflets 3, blades obovate or obtriangular, 0.5–2.5 × 0.3–2.5 cm, base cuneate, veins fine, margins denticulate, apex rounded to emarginate, surfaces glabrous. Peduncles 1.5–4 cm. Inflorescences axillary or terminal, 15–50-flowered, globose, 1–1.8 × 1–1.8 cm; involucres a narrow rim, to 0.2 mm. Pedicels reflexed in fruit, 3–6 mm; bracteoles narrowly oblan­ceolate, 3–6.5 mm. Flowers 6.5–9 mm; calyx oblong, 3–5 mm, glabrous or pubescent, veins 5–10, tube 1–2.5 mm, lobes ± equal or unequal, triangular-lanceolate, recurved in fruit, margins green or purple, apex acute to acuminate, orifice open; corolla pink or white, 6–9 mm, banner obovate-oblong, 6–9 × 1–2 mm, apex acute to emarginate. Legumes linear-oblong, 3–4.5 mm. Seeds 1–5, yellow or pale or dark brown, oblong, 1 mm, smooth. 2n = 16.

Phenology: Flowering Mar–Oct.
Habitat: Roadsides, lawns, fields, waste places.
Elevation: 0–200 m.

Distribution

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Introduced; Ala., Fla., Ga., La., Miss., Tenn., Tex., s Europe, w Asia, n Africa.

Discussion

Trifolium nigrescens was shown, using molecular markers, to consist of three subspecies and to hybridize readily with T. repens (W. M. Williams et al. 2001). It was first introduced as a potential crop species in the early 1950s and is cultivated widely in the southeastern United States as a forage crop and as a nitrogen source in roadside grass plantings (C. S. Hoveland 1960).

Selected References

None.

Lower Taxa

None.