Trifolium arvense, L.

49. T. arvense L. View in CoL , Sp. Pl. 769 (1753).

Annual or biennial; stems 4-40 cm, erect or diffusely branched, whitish- or reddish- pubescent, rarely glabrescent. Upper leaves sessile, their leaflets 5-20 mm, linear-oblong. Lower stipules lanceolate-subulate, the upper subulate from an ovate base. Heads up to 20 mm, numerous, ovoid or oblong, pedunculate, with numerous, densely sericeous flowers. Calyx 3 -5-7(-9) mm, the tube globose in fruit, often covered with dense hairs, rarely glabrescent; teeth 1—3(—5) times as long as the tube, reddish, subequal, setaceous, with long hairs. Corolla c. 4 mm, whitish or pink, much shorter than the calyx. 2« = 14. Dry places; somewhat calcifuge. Most of Europe except the extreme north. All except Fa Is Sb. Very variable in habit, indumentum, pigmentation, size and shape of the leaflets and length of the calyx-teeth. Severaltaxa are recorded over most of Europe. Plants with smaller and less hairy calyx (3 - 5-4- 5 mm) are often called T. gracile Thuill. , FI. Paris ed. 2, 383 (1799); they seem most frequentin W. Europe but occur sporadically elsewhere. T. longisetum Boiss. & Balansa in Boiss., Diagn. Pl. Or. Nov. 3 (6): 47 (1859), with calyx-teeth 4-5 times as long as the tube may deserve recognition as a subspecies of the Mediterranean region.