A new Ceropegia species from Yemen, and reconsideration of the status of C. arabica, C. barbigera and C. powysii (Apocynaceae: Asclepiadoideae-Ceropegieae)

Euphorbia nicaeensis All. is a Mediterranean herbaceous perennial species that flourishes in different environments and successional stages. Sampled from a population in the Herault department (France), adult plants displayed three types of variation in the architecture of the inflorescence axes. The relative proportions of the three types in the different patches are more related to ecological conditions (density of vegetation cover, substrate, successional stage of the patch) than to the age of individuals. Large differences in flowering times and in the quantity of seeds produced between the three architectural types, within and between patches were observed. These differences, however slight, may be related to an intraspecific differentiation tendency induced by the local environment heterogeneity.