Description: Erect annual or perennial herbs, sometimes shrubs.
Leaves alternate, occasionally opposite below, entire to lobed, with 3 main veins.
Heads large and sunflower-like, solitary, on long peduncles swollen below involucre; heads hemispherical or broadly campanulate; involucral bracts 2–5-seriate, graduated or subequal, ribbed, outer leathery, inner herbaceous or papery; receptacle convex, with concave or conduplicate persistent scales enfolding the achenes. Ray florets sterile, ligules bright yellow. Disc florets bisexual, fertile, 5-toothed, pubescent, yellow. Anthers ± sagittate at the base, apical appendage scarious and ovate. Style branches ± flattened, papillose within, hairy on outside, tips sterile.
Achenes oblong, four-angled; pappus usually of two awns and/or scales.
Distribution and occurrence: World: c. 5 species, tropical America. Australia: 2 species (naturalized), Qld, N.S.W.
Text by L. Murray
| ||Key to the species|| |
|1||Involucral bracts oblong to ovate, 3- or 4-seriate; flower heads 10–15 cm diam.; naturalized in coastal districts||Tithonia diversifolia|
|Involucral bracts linear to lanceolate, 2- or 3-seriate; flower heads 4–8 cm diam.; naturalized on Western Slopes||Tithonia rotundifolia|