Knotweed spineflower

Acanthogonum polygonoides (Torrey & A. Gray) Goodman

Plants generally greenish. Invo-lucres 2-2.5 mm; prominent teeth with awns 1.5-2 mm. 2n = 40.

Flowering Apr-Jun. Sandy to gravelly mostly volcanic soils, mixed grassland communities, oak-pine or montane conifer woodlands; 100-1500 m; Calif.

Variety polygonoides occurs from Modoc County to Calaveras County in the Sierra Nevada, in the Sacramento Valley, and in the Coast Ranges from Lake County to Santa Barbara County. In San Luis Obispo and Monterey counties, knotweed spineflower is on sandstones or conglomerates rather than volcanic substrates. All populations are widely scattered and the plants are mostly rare to infrequent.