Plants greenish to grayish, arachnoid to ± sericeous. Stems (1-)2-10, ascending to ± prostrate; proximal internode lengths mostly 1-2(-3) times leaf lengths. Capitular leaves ± spreading, mostly not appressed to heads, spatulate to obovate, widest in distal ¹/3, longest 6-15 mm, lengths mostly 2-5 times widths, 1.5-2.5(-3) times head heights. Heads ± spheric, largest 3-5.5 mm. Receptacles unlobed. Pistillate paleae individually visible through indument, longest mostly 1.5-2.7 mm. Staminate corollas 0.8-1.5 mm, lobes mostly 5. Cypselae narrowly obovoid, somewhat compressed, 0.7-1.2 mm.

Flowering and fruiting late Mar-early Aug. Dry or seasonally moist, barren to wooded slopes, flats, often disturbed sites (foot paths, road beds, burns), sometimes near vernal pools toward s; 0-2100 m; B.C.; Calif., Idaho, Oreg., Wash.; Mexico (Baja California).

Psilocarphus tenellus is relatively common in the Californian Floristic Province from northwestern Baja California to southwestern Oregon; northward it is scattered to northern Idaho and Vancouver Island, British Columbia. It has been of conservation concern in Canada (J. M. Illingworth and G. W. Douglas 1994b).