Annuals, 30-70 cm. Stems usually 1, sparingly branched distally, weakly winged, glabrous or sparsely hairy. Leaves glabrous or sparsely hairy; blades all lance-linear, entire or coarsely toothed. Heads 1-15(-25) per plant, in paniculiform arrays. Peduncles 4-13 cm, glabrous or sparsely to moderately hairy. Involucres globoid to ovoid, 11-16 × 14-20 mm. Phyllaries sparsely to densely hairy. Ray florets 12-18, pistillate, fertile; corollas usually yellow, sometimes yellow with purple streaks, 10-20 × 5-13 mm. Disc florets 300-500(-700+); corollas yellow proximally, yellow to purple to dark blue-purple distally, 3.2-3.6 mm, lobes 5. Cypselae 2-2.9 mm, moderately hairy; pappi of 6-7 entire, aristate scales 1.5-2 mm. 2n = 30. Flowering Jul-Sep. Pine forests, edges of wet places such as bogs, ponds, lakes, ditches; 1800-2400 m; Ariz.
General: Annual, 30-70 cm tall; stems usually solitary, sparsely branched above, glabrous or sparsely pubescent. Leaves: Mostly cauline, alternate, lance-linear, 5-20 cm long, 0.5-1 cm wide, the basal blades larger than cauline, glabrous to sparsely pubescent, margins entire to coarsely toothed, bases somewhat decurrent, the stems appearing winged below the leaves. Flowers: Heads arranged in an open to dense corymb, rarely solitary; involucre broadly urn-shaped to rounded, 6-11 mm long, 8-20 mm wide; phyllaries in 5-6 series, reflexed, spreading, or appressed, filiform, linear, or narrowly lanceolate, the apex usually with a loop or hook, surfaces resinous; flowers June-October. Fruits: Achene, top-shaped, 2-2.9 mm long, pubescent, with 8-10 ribs; pappus of 6-7 awl-like scales. Ecology: Riparian habitats, lake shores, wet areas, pine forests; 2100-2700 m (7000-9000 ft); Apache, Cochise, Coconino, Gila and Yavapai counties; found only in Arizona. Notes: Hymenoxys hoopesii is similar to Helenium arizonicum but typically occurs higher in elevation in meadows and on open slopes, and can be distinguished by its gland-dotted leaf blades, peduncles woolly pubescent near the involucres, green to often purple-reddish tinted stems, and wholly yellow heads. Helenium autumnale (common sneezeweed) is distinguished by strongly decurrent leaf bases (stems appear strongly winged); numerous heads (5- 100); perennial habit. It occurs along roadsides, water bodies, and fields in Apache, Coconino, Navajo, and Yavapai counties. Editor: Springer et al. 2008