Euphorbia humifusa, Willd.

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 : 216

4. E. humifusa Willd. , Enum. Pl. Hort. Berol., Suppl. 27 (1813).

Procumbent, glabrous, more or less glaucous annual, with 4 branches from the base; branches up to 13 cm. Leaves (2-)5-8(-9-5) x (1—)2—4(—5) mm, ovate, obtuse, asymmetrical at base, serrulate, especially in the upper half; petiole 0-5-1 mm. Stipules c. 1 mm, subulate-filiform. Glands transversely ovate to suborbicular, concave, stipitate. Capsule 1 -5 x 1 -5-2 mm, transversely rugulose, nearly smooth. Seeds 1 -2 mm, ovoid, smooth, mottled grey-brown. Stony or disturbed ground. S. Ukraine and S.E. Russia; naturalized elsewhere in parts of S. & C. Europe as a weed and ruderal. Rs (W, K, E) [Au Co?Cz Ga Ge He Hu It?Ju Po Rm Sa Si.] (W. & C. Asia.)

E. serpens Kunth in Humb., Bonpl. & Kunth, Nov. Gen. Sp. 2: 52 (1817), has smaller, entire leaves, stipules often connate, and smaller, more or less quadrangular seeds. It is native of America, and occurs frequently as a casual in S. France and Spain, where it is perhaps locally naturalized.