Asteraceae (tribe Heliantheae) subtribe Melampodiinae

Annuals, perennials, or subshrubs [treelets], 10–120(–300+)[–1200+] cm. Leaves cauline; opposite; petiolate or sessile; blades mostly deltate or ovate to lanceolate or linear (and most intermediate shapes), sometimes palmately or pinnately lobed, ultimate margins dentate, denticulate, entire, or toothed, faces glabrous or hairy, often gland-dotted. Heads radiate, borne singly or in open, corymbiform arrays. Calyculi 0. Involucres cylindric or ovoid to hemispheric (sometimes cupulate). Phyllaries persistent and/or falling, 8–25+ in 2 series (outer 2–6 distinct or connate, herbaceous, contrasting with distinct, more membranous to scarious, inner ones, each of the inner often enveloping its subtended ray ovary, maturing with the cypsela, forming a perigynium). Receptacles flat to convex, conic, or columnar (mostly 1–2 mm), paleate (paleae lanceolate to spatulate or obovate, scarious to membranous, often conduplicate, often falling together as a unit with spent disc florets). Ray florets 3–20+, pistillate, fertile; corollas yellow, orange, or white. Disc florets 3–150+, functionally staminate; corollas yellow, orange, or whitish, tubes shorter than funnelform or campanulate throats, lobes 5, deltate; anther thecae dark; stigmatic papillae 0. Cypselae weakly to strongly compressed, obovoid to ± prismatic (often 4-angled; sometimes each enclosed within a smooth, bullate, tuberculate, or prickly perigynium derived from its subtending phyllary); pappi 0 (or rudimentary).

Distribution

Subtropical, tropical, and warm-temperate New World.

Discussion

Genera 5, species 80 (3 genera, 11 species in the flora).

Circumscription of Melampodiinae in the sense of H. Robinson (1981) is narrower than the traditional one (e.g., T. F. Stuessy 1973), which included most non wind-pollinated genera of Heliantheae with functionally staminate disc florets.

Selected References

Stuessy, T. F. 1973. A systematic review of the subtribe Melampodiinae (Compositae, Heliantheae). Contr. Gray Herb. 203: 65–80.

Lower Taxa

Acanthospermum, Melampodium, Smallanthus

Key

1	Cypselae: each shed separate from its subtending phyllary	Smallanthus
1	Cypselae: each enclosed within and shed with perigynium formed from inner, subtending phyllary (the units called fruits)	> 2
2	Heads borne singly, usually pedunculate; fruits smooth or bullate to tuberculate (1–4 mm)	Melampodium
2	Heads often in clusters of 2–3, mostly sessile; fruits ± prickly (4–8 mm)	Acanthospermum