Flowers: clusters loose. Calyces 1.5–3 mm, longer than corolla tube, divided 2/3 length, lobes lanceolate, bases not over­lapping, apex acute.

Flowering Jun–Sep. Hosts: Ambrosia, Gutierrezia, Helian­thus, Iva annua, Solidago; ­ Tex.; Mexico; introduced in South America.

Variety longisepala is currently included in North American lists of noxious weeds although is not known to attack any crops. It was introduced to South America, where it is more common and sometimes weedy.