Pterochiton Torrey & Frémont in J. C. Frémont, Rep. Exped. Rocky Mts., 318. 1845; Atriplex [unranked] Canescentes Standley; Atriplex [unranked] Confertifoliae Standley; Atriplex sect. Deserticola (Ulbrich) McNeill, Bassett, Crompton & Taschereau; Atriplex [unranked] Nuttallianae Standley; Obione Gaertner sect. Deserticola Ulbrich; Obione subg. Pterochiton (Torrey & Frémont) Ulbrich

Plants typically dioecious, woody, low to tall. Leaves with Kranz anatomy, usually alternate, petiolate or sessile; blade variously shaped, margin entire, hastately lobed, or variously dentate. Staminate flowers in axillary glomerules or more typically in naked terminal spikes or spicate panicles. Pistillate flowers lacking perianth. Fruiting bracteoles sessile or stipitate, united beyond middle to apex, variously shaped, winged or wingless, margin entire or toothed to lobed, faces tuberculate or lacking tubercles. Seeds erect; radicle superior or sublateral (in A. hymenelytra, A. lentiformis, and A. torreyi).

Species 14 (14 in the flora): United States, Mexico.

E. Ulbrich (1934) circumscribed section Deserticola to include all of the shrubby species of Atriplex except for Atriplex canescens, which he included within Obione subgenus Pterochiton. The name Deserticola was taken by J. McNeill et al. (1983) to include not only A. canescens per se, but representatives of other groups containing woody taxa, as treated by P. C. Standley. Atriplex canescens is known to form hybrids with numerous other taxa of woody Atriplex. Thus, most of the woody species are in some large part closely allied and capable of hybridization to a greater or lesser extent. Members of the subgenus, despite their near relationships, also show affinities that lead back through time to some ancestor or ancestors common to both them and with those of subgenus Obione. They do not, however, appear to have arisen as end points of evolution from various places within that subgenus, i.e., the subgenus Pterochiton appears to be monophyletic.

SELECTED REFERENCE

Henrickson, J. 1988. A revision of the Atriplex acanthocarpa complex (Chenopodiaceae). SouthW. Naturalist 33: 451-463.