Trifolium arvense
Sp. Pl. 2: 769. 1753.
Herbs annual, 5–30 cm, villous. Stems erect, branched distally. Leaves palmate; stipules linear-lanceolate to ovate-oblong, 0.5–0.8 cm, margins entire, apex filiform; petiole 0.4–4.5 cm; petiolules 1+ mm; leaflets 3, blades linear-oblong to narrowly elliptic, 1–2 × 0.2–0.5 cm, base cuneate, veins fine, margins denticulate distally, apex mucronate, surfaces hairy. Peduncles 0.5–2.5 cm. Inflorescences axillary or terminal, 30–100-flowered, ovoid or cylindric, elongate in fruit, 1–2.3 × 0.9–1.2 cm; involucres absent. Pedicels straight, to 0.5 mm; bracteoles obtuse, to 0.1 mm. Flowers 5–8 mm; calyx campanulate, 5–8 mm, villous, veins 10, tube 1.2–1.8 mm, lobes purple or pink, subequal, setacous, orifice open, hairy; corolla white to pink, 3–6 mm, much shorter than calyx, banner narrowly ovate-elliptic, 5–5.5 × 1–1.5 mm, apex obtuse. Legumes ovoid, leathery distally, transversely dehiscent, 1.5–2 mm. Seeds 1, yellow, globose, 1 mm, smooth, glossy. 2n = 14.
Phenology: Flowering Mar–Jun.
Habitat: Waste places, roadsides, fields.
Elevation: 0–1300 m.
Distribution
Introduced; St. Pierre and Miquelon, B.C., N.B., Nfld. and Labr. (Nfld.), N.S., Ont., P.E.I., Que., Ala., Ariz., Ark., Calif., Conn., Del., D.C., Fla., Ga., Idaho, Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont., N.H., N.J., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., R.I., S.C., Tenn., Tex., Utah, Vt., Va., Wash., W.Va., Wis., s Europe, w Asia, n Africa, introduced also in s South America (Argentina, Chile, Uruguay), s Africa, Pacific Islands (New Zealand), Australia.
Discussion
Trifolium arvense is widely distributed throughout the flora area. It was listed among cultivated clovers by F. J. Hermann (1953); J. M. Gillett (1985) expressed doubt that it had been cultivated.
Selected References
None.