Annuals, 25-60 cm. Stems erect, sparsely hispid. Leaves mostly cau-line; mostly alternate; petioles 1.2-5 cm; blades ovate to lance-ovate, 4.5-13 × 1-4 cm, bases cuneate, margins entire, abaxial faces sparse-ly hispid, not gland-dotted. Heads usually borne singly. Peduncles 4-9 cm. Involucres hemispheric, 20-27 mm diam. Phyllaries 11-23, laceolate to lance-linear or lance-ovate , 17-33 × 1-2.9 mm (notably surpassing discs), (margins ± ciliate ) apices attenuate, abaxial faces usually sparsely hispid to hispidulous. Paleae 7-8 mm, apices 3-toothed (middle teeth attenuate, apices purplish, ± hispid). Ray florets 7-12; laminae 18-37 mm. Disc florets 25+; corollas 6.8-7.5 mm, lobes reddish; anthers dark, appendages dark (style branches reddish). Cypselae 4.6-9 mm, appressed hairy; pappi of 2 linear scales 2-4.5 mm plus 4-6 scales 1-3.5 mm. 2n = 34.

Flowering spring-fall. Sand dunes; 1300-1500 m; Ariz., Utah.

L. H. Rieseberg (1991) provided evidence that Helianthus anomalus is a hybrid species derived from H. annuus and H. petiolaris, and subsequent work has confirmed and extended that hypothesis.