Helenium microcephalum

de Candolle

in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 5: 667. 1836.

Common names: Smallhead sneezeweed
Treatment appears in FNA Volume 21. Treatment on page 433. Mentioned on page 428.

Annuals, 25–120 cm. Stems 1(2–10), branched distally, moderately to strongly winged, glabrous or sparsely hairy. Leaves glabrous or sparsely to moderately hairy (basal withered by flowering); proximal and mid blades narrowly elliptic to narrowly oblong-elliptic, usually serrate to undulate-serrate, sometimes deeply toothed or laciniate; distal blades narrowly elliptic to narrowly oblong-elliptic, serrate to undulate-serrate. Heads 20–300+ per plant, in paniculiform arrays. Peduncles 1.8–8 cm, moderately hairy. Involucres globoid to usually ovoid, 4–12 × 4–12 mm. Phyllaries (connate proximally) moderately hairy. Ray florets 7–13, pistillate, fertile; corollas usually yellow throughout, sometimes reddish proximally and yellow distally, 2.6–9.1 × 1.5–6.7 mm. Disc florets 120–400+; corollas yellow to yellow-green proximally, brown to reddish brown distally, 1.2–2.4 mm, lobes (4–)5. Cypselae 0.7–1.4 mm, moderately hairy; pappi of usually 6 entire, non-aristate scales (0.2–)0.3–0.7 mm.



Ariz., N.Mex., Okla., Tex., n Mexico.


Varieties 2 (2 in the flora).

Selected References



1 Peduncles 1–3.5 cm, projecting terminal heads barely beyond foliage; involucres 4–8 × 4–8 mm Helenium microcephalum var. microcephalum
1 Peduncles 1.5–8 cm, usually projecting terminal heads well beyond foliage; involucres 8–12 × 8–12 mm Helenium microcephalum var. oöclinium