Chamaesyce

Chamaesyce is former genus of plants in the family Euphorbiaceae, now subsumed into the genus Euphorbia as Euphorbia sect. Anisophyllum in the subgenus Chamaesyce. The section contains around 350–365 species (around 210 New World and 140 Old World) that were formerly in the genus Chamaesyce. Plants in this section are known for their prostrate, branching habit and include probably best known for E. maculata, a temperate weed known as spotted spurge found worldwide, and E. hirta, a pantropical weed. Many of the species are known as sandmats. The section Anisophyllum is very closely related to plants like Euphorbia pulcherrima, the popular poinsettia.

Euphorbia sect. Anisophyllum differs from other Euphorbia species in a number of characteristics. Perhaps the most important is the presence of C4 photosynthesis in all but one subsection (subsection Acutae, which represents a basal clade that is made up of species with intermediate C2 photosynthetic pathways). Other characteristics include sympodial branching, dorsi-ventral stems, asymmetric leaves, non-glandular stipules, and ecarunculate seeds.