Acanthogonum Torrey in War Department [U.S.], Pacif. Railr. Rep. 4(5): 132. 1857; Chorizanthe sect. Chorizanthella Parry

Plants prostrate to spreading or erect. Leaf blades oblanceolate to elliptic or round. Stems not disarticulating at each node. Inflorescences: bracts awned or awnless. Involucres cylindric, campanulate, or urceolate, not ventricose basally, 3-angled, 3-ribbed, 3-, 5-, or occasionally 6-toothed, without membranous or scarious margins; awns equal, sometimes anterior one longest. Flowers 1(-2); perianth white to rose or yellow, thinly to densely pubescent; stamens 3, 6, or 9; filaments adnate faucially at or near top of floral tube. Achenes brown to black, lenticular or 3-gonous.

Species 5 (5 in the flora): w United States, nw Mexico.

G. J. Goodman (1934) assigned Chorizanthe polygonoides to Acanthogonum, which previously included C. rigida and C. corrugata (see below). J. L. Reveal and C. B. Hardham (1989b) considered that taxon to represent a section within Chorizanthe, expanded it further to include both C. orcuttiana and C. watsonii, and divided it into five subsections. Section Acanthogonum differs from sect. Ptelosepala by having involucral tubes that are not both 6-ribbed and 6-toothed at the same time.