Helenium thurberi A. Gray

Annuals, 40–100 cm. Stems usually 1, branched distally, moderately winged, sparsely hairy proximally, moderately hairy distally. Leaves glabrous or sparsely hairy (basal leaves withered by flowering); proximal blades lanceolate to lance-linear, usually irregularly laciniate; mid and distal blades lance-linear, entire. Heads 10–75(–120+) per plant, in paniculiform arrays. Peduncles 3–10 cm, moderately hairy. Involucres ovoid to conic, 6–10 × 5–10 mm. Phyllaries (strongly connate proximally), moderately hairy. Ray florets 0. Disc florets 225–500+; corollas yellow-green proximally, brown to reddish brown distally, 1–1.3 mm, lobes 4. Cypselae 0.9–1.2(–1.5) mm, moderately hairy; pappi of 6(–7) entire, non-aristate scales 0.2–0.5 mm. 2n = 26.

Helenium thurberi A. Gray, Proc. Am. Acad. 19: 32. 1883
Heleniastrum Thurberi Kuntze, Rev. Gen. 342. 1891.
A branched annual; stem 5-10 dm. high, puberulent, winged; lower leaves oblanceolate, 5-8 cm. long, more or less puberulent, sharply dentate; upper leaves narrowly lanceolate or linear-lanceolate, entire; heads discoid, corymbose; peduncles slender, 5-10 cm. long; involucral bracts lance-subulate, 5-7 mm. long; disk globose or slightly ovoid, 7-8 mm. broad, fuscous; corollas less than 1.5 mm. long; tube minute; throat campanulate; achenes 1 mm. long, hirsute on the angles; squamellae rounded-ovate, obtuse, one-third as long as the corolla.
Type locality: Southern Arizona. Distribution: Arizona to Chihuahua and Tepic.

Helenium thurberi is a North American plant in the sunflower family, commonly known as Thurber's sneezeweed. It is native to Mexico (Baja California Sur, Sinaloa, Nayarit, Chihuahua) and the southwestern United States (Arizona).

Helenium thurberi is an annual herb up to 100 cm (39.5 in) tall, with small wings running down the sides of the stems. Leaves are lance-shaped. One plant can produce up to 120 flower heads, in a branching array. Each head has an egg-shaped or conical disc that may contain 500 or more minuscule disc flowers each 1.0–1.3 mm (0.039–0.051 in) across, each yellow toward the bottom but brown or reddish-brown toward the tip. There are no ray flowers.

Helenium thurberi là một loài thực vật có hoa trong họ Cúc. Loài này được A.Gray mô tả khoa học đầu tiên năm 1883.