[Includes T. erecta L., the common 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.