1. Tetracoccus Engelmann ex Parry, W. Amer. Sci. 1: 13. 1885.
Four-pod spurge [Greek tetra, four, and kokkos, kernel or berry, alluding to 4-lobed capsule in T. dioicus] Four-pod spurge [Greek tetra, four, and kokkos, kernel or berry, alluding to 4-lobed capsule in T. dioicus]
W. John Hayden
Halliophytum I. M. Johnston
Shrubs, usually dioecious, sparingly hairy to glabrescent, hairs simple. Leaves often clustered on axillary short shoots; blade glabrescent. Inflorescences: staminate paniclelike or racemelike thyrses, or fascicles on short shoots; pistillate fascicles on short shoots or flowers solitary. Pedicels present or absent. Staminate flowers: sepals 4–10, sometimes weakly differentiated in 2 whorls; nectary intrastaminal, lobed; stamens 4–10. Pistillate flowers: sepals 5–13, sometimes differentiated in 2 whorls; nectary lobed. Fruits capsules. Seeds oblong, ovoid, or pyriform, with one flattened radial surface if 2 seeds develop per locule, otherwise both radial surfaces rounded, seed coat dry, smooth or wrinkled near hilum. x = 12.
Species 5 (3 in the flora): sw United States, n Mexico.
In addition to the three species treated for the flora area, Tetracoccus includes two Mexican species, T. capensis (I. M. Johnston) Croizat from the extreme tip of Baja California Sur and T. fasciculatus (S. Watson) Croizat from the Chihuahuan Desert.
SELECTED REFERENCE Dressler, R. L. 1954. The genus Tetracoccus (Euphorbiaceae). Rhodora 56: 45–61.