ASTERACEAE

SUNFLOWER FAMILY

David J. Keil, Family Editor and author, except as specified

Annual to tree
Leaves basal or cauline, alternate to whorled, simple to compound
Inflorescence: 1° inflorescence a head, each resembling a flower, 1–many, generally arrayed in cymes, generally subtended by ± calyx-like involucre; flowers 1–many per head
Flowers bisexual, unisexual, or sterile, ± small, of several types; calyx 0 or modified into pappus of bristles, scales, or awns, which is generally persistent in fruit; corolla radial or bilateral (rarely 0), lobes generally (0)4–5; stamens 4–5, anthers generally fused into cylinder around style, often appendaged at tips, bases, or both, filaments generally free, generally attached to corolla near throat; pistil 1, ovary inferior, 1-chambered, 1-seeded, style 1, branches 2, generally hair-tufted at tip, stigmas 2, generally on inside of style branches
Fruit: achene, cylindric to ovoid, generally deciduous with pappus attached
Genera in family: ± 1300 genera, 21,000 species (largest family of dicots): worldwide. Largest family in CA. Also see tribal key to CA genera: Strother 1997 Madroño 44(1):1–28. See glossary p. 25 for illustrations of general family characteristics.

HYMENOXYS

Annual, biennial, perennial herb
Stems erect, simple to much-branched
Leaves simple, basal or alternate, sessile or petioled, entire or divided 1 or more times into linear lobes, dotted with sunken resin glands
Inflorescence: heads generally radiate, solitary or in few–many-headed cymes; involucre hemispheric; phyllaries in 2–3 similar or dissimilar series; receptacle flat to rounded, naked
Ray flowers few–many; corolla yellow, fan-shaped, 3–5-lobed
Disk flowers many; corolla yellow
Fruit obpyramidal, generally 5-angled, hairy; pappus of ± 5 membranous, often awn-tipped scales
Species in genus: 28 species: w North America, South America
Etymology: (Greek: sharp membrane, from pappus)
Horticultural information: TRY.

Native

H. acaulis (Pursh) K.L. Parker var. arizonica (Greene) K.L. Parker

Perennial 8–20 cm from branched caudex
Stems unbranched
Leaves generally all basal, 2–6 cm, linear to narrowly oblanceolate, entire, soft-hairy, especially at base, becoming ± glabrous in age
Inflorescence: heads solitary, scapose; involucre tomentose; outer phyllaries = inner, 5–6 mm, oblanceolate to obovate, free
Ray flowers 8–13; ligule 10–15 mm, bright yellow, fading to cream and ± persistent on fruit
Disk flowers: corolla 3.5–4 mm
Fruit 3–4 mm; pappus scales 5–7, 2–3 mm, obovate, entire or awn-tipped
Chromosomes: 2n=30,60
Ecology: Dry, rocky slopes
Elevation: 1400–2800 m.
Bioregional distribution: San Jacinto Mountains, Desert Mountains
Distribution outside California: to Wyoming, Colorado, Arizona
Flowering time: Apr–Jun