Biennials or perennials, 30-60 cm (monocarpic; sometimes with sparingly branched, woody caudices). Stems 1(-5), green throughout or sometimes purple-red-tinted proximally, branched distally, usually densely sericeous. Leaves: blades simple or lobed (lobes 3), usually densely sericeous, gland-dotted; mid leaves simple or lobed (lobes 3, terminal lobes 1.8-3.5 mm wide). Heads 10-85+ per plant, in paniculiform to corymbiform arrays. Peduncles 3-9 cm, usually densely sericeous. Involucres hemispheric to campanulate, 8-10 × 10-13 mm. Phyllaries in 2 series, unequal; outer 10-14(-18), basally connate 1/4-1/2 their lengths, lanceolate, obovate, or ovate 5-7 mm, apices acuminate to acute; inner phyllaries 13-16(-22), obovate, 4-5 mm, apices mucronate. Ray florets 10-16; corollas yellow, 10-15 × 4.5-6.5 mm. Disc florets 50-100+; corollas 3.5-4 mm. Cypselae narrowly obpyramidal, 2.1-3 mm; pappi of 5(-6) obovate, aristate scales 2.5-3 mm. 2n = 30.
Flowering (Jun-)Jul-Aug(-Sep). Roadsides, open areas, edges of forests; 2100-2800 m; Ariz., Utah.
Hymenoxys subintegra grows mainly on the Kaibab Plateau north of the Grand Canyon in Arizona and in western Kane County, Utah.
General: Biennial or perennial, 30-60 cm tall; stems mostly solitary, sometimes few, erect, branched above, green throughout, sometimes purple-red tinged at the base, usually densely silky pubescent; caudex woody, sparingly branched.
Leaves: Basal and cauline, alternate, simple and/or 3-lobed, 3-8 cm long, 2-6 mm wide, the terminal lobe 1.8-3.5 mm wide, usually silky pubescent, gland-dotted.
Flowers: Heads mostly 80-250, arranged in corymb-like arrays; peduncles more-or-less hairy; involucre campanulate, 7-11 mm long, 7-14 mm wide; phyllaries in 2 series, unequal, the outer series strongly keeled and connate basally for half their length; ray flowers 7-9, 7-15 mm long, yellow; disk flowers 25-50 or more, 3-4 mm long, yellow; flowers June-September.c
Fruits: Achene, narrowly obpyramidal, 2.1-3 mm long; pappus usually of 5 obovate, bristle-like scales 2.5-3 mm long.
Ecology: Clearings in ponderosa pine forests, roadsides, open habitats; 1500-2600 m (5000-8500 ft); Coconino and Yavapai counties; southwestern U.S.
Notes: Hymenoxys helenioides (Intermountain rubberweed) is similar to H. subintegra, but is differentiated by its perennial habit, glabrous to sparsely pubescent leaves, and ray flowers that are yellow to yellow-orange. It has been reported in the Lukachukai Mountains in northern Apache County.
Editor: Springer et al. 2008
