Trifolium

Tutin, T. G., Heywood, V. H., Burges, N. A., Moore, D. M., Valentine, D. H., Walters, S. M. & Webb, D. A., 1981, Flora Europaea. Volume 2. Rosaceae to Umbelliferae, Cambridge University Press : 166

Subgen. Trifolium . Flowers ebracteate. Calyx-throat usually more or less closed with a ring of hairs or an annular or 2-lobed callosity. Legume nearly always included in the calyx-tube, 1 - to 2-seeded.