Helianthus neglectus C. B. Heiser

Annuals, 80–200 cm. Stems erect (leafy), ± hispid to glabrate. Leaves cauline; alternate; petioles 7–12 cm; blades deltate-ovate, 7–14 × 7.5–12.3 cm, bases usually ± cordate, sometimes truncate , margins subentire to serrulate, abaxial faces strigose, not gland-dotted. Heads 1–5. Peduncles 10–40 cm. Involucres ± hemispheric, (23–28 ×) 10–14 mm. Phyllaries 25–35, lanceolate, 14–25 × 2.3–4 mm (surpassing discs), apices long-attenuate, abaxial faces strigillose to hispid. Paleae 9–10 mm, 3-toothed (middle teeth ± ciliate or bearded, hairs whitish, 0.3–0.6 mm). Ray florets 21–31; laminae 29–39 mm. Disc florets 150+; corollas 6–6.5 mm, lobes reddish; anthers dark, appendages purplish (style branches reddish). Cypselae 4–5 mm, strigillose to glabrate ; pappi of 2 aristate scales 2.8–3.2 mm. 2n = 34.

Helianthus neglectus is a species of sunflower known by the common names neglected sunflower. It is native to the southwestern United States in southeastern New Mexico and West Texas.

Helianthus neglectus grows on sand dunes and other sandy soil. This wildflower is an annual herb up to 200 cm (almost 7 ft) tall, growing from a thick, fleshy taproot. One plant produces one to five flower heads containing 21-31 yellow ray florets surrounding 150 or more red or purple disc florets.

Helianthus neglectus hybridizes with several other species in the region: H. annuus, H. debilis, and H. petiolaris.

Helianthus neglectus là một loài thực vật có hoa trong họ Cúc. Loài này được Heiser mô tả khoa học đầu tiên năm 1958.