Asclepias L.

Tutin, T. G., Heywood, V. H., Burges, N. A., Moore, D. M., Valentine, D. H., Walters, S. M. & Webb, D. A., 1972, Flora Europaea. Volume 3. Diapensiacea to Myoporaceae, Cambridge: Cambridge University Press : 70-71

4. Asclepias L. 2

Erect herbs with many straight stems. Leaves opposite. Flowers in axillary and terminal umbels. Corolla valvate in bud; lobes deflexed at anthesis. Corona single, with 5 free segments, each with a central adaxial appendage curved over the anthers. Follicles ovoid, usually spiny.

Literature: R. E. Woodson, Ann. Missouri Bot. Gard. 41: 1-211 (1954).