Annuals, 10-120+ cm. Leaf blades 30-120(-250+) mm overall, principal lobes/leaflets 9-25, lanceolate to lance-linear, 15-25(-45+) × 3-8(-12+) mm. Heads borne ± singly. Peduncles 30-100(-150+) mm. Involucres 10-22+ × (3-)5-12+ mm. Ray florets (3-)5-8+ (to 100+ in 'double' cultivars); laminae yellow to orange, red-brown (sometimes particolored: yellow/red-brown), or white (some cultivars), ± flabellate to oval-quadrate, (2-)12-18(-25+) mm. Disc florets (10-)50-120+; corollas 7-12+ mm. Cypselae 6-11 mm; pappi of 0-2, ± subulate-aristate scales 6-12+ mm plus 2-4 distinct or connate, linear-oblong, ± erose scales 2-6+ mm. 2n = 24, 48. Flowering ± year round. Disturbed sites; 0-1000+ m; Ala., Ark., Calif., Conn., Fla., Ill., Kans., Ky., La., Md., Mass., Mo., N.Y., N.C., Ohio, Okla., Pa., S.C., Utah, Vt., Va., Wis., Wyo.; Mexico. Cultivars of Tagetes erecta are widely grown in gardens and, commercially, for cut flowers. They often persist after abandoned plantings. Tetraploid plants (2n = 48) with smaller involucres and wholly or partially red-brown corollas included here in T. erecta have been called T. patula by some botanists.
And T. patula L., the "French" marigold, both native to Mex., are widely cult. in double forms and occasionally escape. T. erecta has yellow or orange heads mostly 6-10 cm wide on fistulous peduncles, the invol ca 2 cm. T. patula has smaller, usually partly or wholly deep red-orange heads 3.5-5 cm wide on scarcely fistulous peduncles, the invol ca 1.5 cm.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.