Cosmos Cav.
Annual or perennial herbs, rarely somewhat woody. Lvs opposite, simple and entire to lobed or pinnatisect, or 1-3-pinnate. Capitula pedunculate, solitary or in loose cymes. Involucral bracts in 2 rows; outer row usually foliaceous; inner row membranous. Receptacle flat; scales present. Outer florets sterile, ligulate, usually rose or violet to purple, rarely orange, yellow or white. Inner florets ⚥, tubular. Achenes all similar, usually fusiform, sometimes linear, ± square in section, sometimes compressed, not winged, attenuated into beak at apex; pappus 0, or of 2-8 awns, usually with retrorse barbs, sometimes with antrorse barbs or hispid.
Key
1
Lvs (1)-2-pinnate with linear or rarely narrow-lanceolate leaflets; ligules pale to deep mauve-pink, pink or white
Lvs 1-pinnate and again 1-2-pinnatisect with subulate to ovate segments; ligules bright orange- yellow
26 spp., N., C., and S. America. Naturalised spp. 2.
