Trichocoronis riparia (Greene) Greene

Plants sometimes colonial. Leaves mostly 10–25 mm. Involucres 1.8–2.5 mm. Corollas ca. 1 mm. Cypselae ca. 1 mm. 2n = 30.

Flowering Feb–Jul(–Oct). Edges of ponds, streams, ditches, wet depressions in clay and sand, prairies, brushlands, roadsides; 0–20 m; Calif., Tex.; Mexico.

The California populations of Trichocoronis wrightii have been described as "adventive" and "native to Texas." Trichocoronis wrightii var. wigginsii R. M. King & H. Robinson is regarded as endemic to Sierra de la Giganta in Baja California Sur. It differs from var. wrightii in its taller, mostly unbranched stems, greater number of flowers per head, and less thickened carpopodial cells (King and Robinson 1970b).