Trifolium hybridum
Sp. Pl. 2: 766. 1753.
Herbs perennial, 10–70 cm, glabrous or sparsely hairy. Stems erect or ascending, branched. Leaves palmate; stipules obovate or lanceolate, 1–2.5 cm, margins entire or toothed, apex long-acuminate; petiole 1–21 cm; petiolules 1 mm; leaflets 3, blades usually obovate or ovate, rarely rhombic, 1–4 × 1–2.5 cm, base cuneate, veins prominent, margins sharply serrate, apex broadly acute, obtuse, or emarginate, surfaces glabrous. Peduncles 2–10 cm. Inflorescences terminal or axillary, 10–70+-flowered, globose to subglobose, 1–2.5 × 1–2.5 cm, rachis not prolonged beyond flowers; involucres absent. Pedicels strongly reflexed, 2–3.5 mm; bracteoles lanceolate, 1 mm. Flowers 8–12 mm; calyx campanulate, 3.5–4 mm, glabrous or sparsely hairy, veins 10, tube 1.5–2 mm, lobes unequal, lanceolate-subulate, orifice open; corolla pale to dark pink, 7–10 mm, banner ovate-oblong, 6.5–10.5 × 4–6 mm, apex rounded-denticulate. Legumes stipitate, ellipsoid, 3–7 mm. Seeds 2–4, tan, brown, or red-brown, mitten-shaped, 1–1.4 mm, smooth, dull. 2n = 16.
Phenology: Flowering May–Oct.
Habitat: Roadsides, open woods, edges, fields, meadows, waste places.
Elevation: 0–1800 m.
Distribution
Introduced; Greenland, St. Pierre and Miquelon, Alta., B.C., Man., N.B., Nfld. and Labr., N.W.T., N.S., Ont., P.E.I., Que., Sask., Yukon, Ala., Alaska, Ariz., Ark., Calif., Colo., Conn., Del., D.C., Fla., Ga., Idaho, Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Utah, Vt., Va., Wash., W.Va., Wis., Wyo., Europe, w Asia, introduced also in South America, Europe, elsewhere in Asia, Africa, Pacific Islands, Australia.
Discussion
Trifolium hybridum is widely cultivated as a forage crop. It may cause dermatitis in humans (J. W. Hardin and J. M. Arena 1974) and is implicated as a cause of dermatitis and biliary fibrosis in horses (C. Fisher 1995); the connection between the clover and the diseases is inconclusive (P. N. Nation 1989).
Selected References
None.