Trans. Amer. Philos. Soc., n. s. 7: 315. 1840.
Annuals, biennials, or short-lived perennials, 10–250 cm (atypical, spring-blooming, dwarf dune plants have short stems; perennating from proximal stem nodes in south; aromatic); taprooted. Stems 1–5+, ascending to erect (strict, 0.9–1.7 cm diam., only distal lateral branches developing in larger plants), moderately to densely hispido-strigose, more so proximally, moderately to densely stipitate-glandular, more so distally. Leaves: basal and proximal cauline petiolate (petioles 3–7 cm, bases auriculate-clasping), blades ovate or elliptic to oblong, 50–80 × 20–30 mm, margins flat or somewhat undulate, coarsely serrate to serrulate or entire, proximally long-ciliate, apices acute, faces moderately to densely long-hispido-strigose; distal sessile, blades oblong-lanceolate to lanceolate, 20–40 × 20–30 mm, reduced distally, margins often undulate, coarsely serrate. Heads 10–110+, in corymbiform arrays, becoming paniculiform with age, branches ascending, usually relatively short compared to plant height. Peduncles 10–65 mm, sparsely to densely hispido-strigose, densely stipitate-glandular; bracts 0–3, linear-lanceolate to linear, reduced distally. Involucres campanulo-hemispheric, 6–9 mm. Phyllaries in 4–6 series, linear-lanceolate, unequal, margins scarious, faces strigose, densely stipitate-glandular. Ray-florets 20–40; laminae 5–8 × 1–2 mm. Disc-florets 30–75; corollas 4–6 mm, lobes 0.5–0.8 mm. Cypselae dimorphic, (ray) 2–5 mm, faces glabrous or slightly strigose on angles, (disc) 4–6 mm, faces moderately to densely strigose; pappi 0 (ray) or (disc) stramineous to rusty brown, outer bristles 0.4–0.7 mm, inner 6–9 mm, longest weakly clavate. 2n = 18.
Phenology: Flowering Apr–Dec(–Jan).
Habitat: Sandy and gravelly soils, dunes, disturbed ground, roadsides, vacant lots, fields
Elevation: 0–100(–900) m
Ariz., Calif., Nev., Utah, in Pacific Islands (Hawaii)
Heterotheca grandiflora is common in California, rare and probably introduced in Arizona, Nevada, and Utah, and introduced in Hawaii. Rosette plants can bloom in the spring.
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