Galinsoga Ruiz & Pav.
Annual herbs. Lvs opposite, simple, usually serrate, 3-veined. Capitula pedunculate, in loose to congested dichasial cymose clusters. Involucral bracts in 1-3 rows. Receptacle conic; scales present. Outer florets ♀, ligulate, white to reddish or purple. Inner florets ⚥, tubular. Achenes dimorphic. Ray achenes flattened; pappus of laciniate scales, longer on one side, reduced to hairs, or 0. Disc achenes usually subterete; pappus of subulate to lanceolate, obtuse to aristate, laciniate scales, reduced to bristles, or 0.
Key
14 spp., Mexico, C. and S. America. Naturalised spp. 2.
Galinsoga has been revised recently by Canne, J. M., Rhodora 79 : 319-389 (1977), and that treatment is followed here. Ripe frs are essential for identification and can usually be found on flowering plants.