Tithonia

Annuals, perennials, subshrubs, or shrubs [trees], 70-500[-700] cm. Stems erect, branched. Leaves all or mostly cauline; opposite (proximal) or mostly alternate; petiolate or sessile; blades often (1-), 3-, or 5-nerved, mostly deltate or pentagonal [lanceolate, linear], sometimes 3- or 5-lobed, bases ± truncate or auriculate [attenuate] (sometimes decurrent onto petioles), ultimate margins serrate to crenate, faces glabrate, ± hirsute, pilose, soft-pubescent, or villous, often gland-dotted. Heads borne singly (peduncles usually distally dilated, fistulose). Involucres campanulate to hemispheric, 10-20+ mm diam. Phyllaries persistent, 12-28+ in 2-5 series (linear to broadly rounded, unequal to subequal, apices acute to rounded). Receptacles hemispheric to convex, paleate (paleae persistent, embracing cypselae, striate, ± 3-toothed, middle teeth larger, stiff, acute or acuminate to aristate). Ray florets 8-30, neuter; corollas yellow or orange. Disc florets 40-120[-200+], bisexual, fertile; corollas yellow, tubes shorter than throats (bases of throats bulbous and hairy), lobes 5, ± triangular (anthers black, brown, or tan, bases cordate-sagittate, appendages ovate; style branches relatively slender, appendages penicillate or lanceolate to attenuate). Cypselae (black or brown) ± compressed or flattened, often 3- or 4-angled or biconvex, ± cuneiform in silhouette (sometimes with basal elaiosomes); pappi 0, or ± coroniform (of ± connate scales, 1-2 scales sometimes subulate to aristate). x = 17.