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.

HELIANTHELLA

Perennial from taproot and caudex
Stems 1–several, erect
Leaves basal and cauline, alternate or opposite; petioles short to long; blades generally 3-veined, linear to ± ovate, entire, ± scabrous
Inflorescence: heads radiate, 1–few, in cymes; peduncles long, with 0–few leaf-like bracts; involucre hemispheric; phyllaries in 2–3 series, free; receptacle flat to ± convex, chaff scales folded around ovary, entire, obtuse, tip hairy
Ray flowers sterile; corolla yellow; style 0
Disk flowers many; corolla and anthers yellow or purple; style tips short-triangular
Fruit thick or compressed; pappus 0 or 2 awns 1–2 mm (sometimes also crown of low scales)
Species in genus: 8 species: w North America
Etymology: (Latin: diminutive of Helianthus )
Reference: [Weber 1952 Amer Midl Naturalist 48:1–35]

Native

H. castanea Greene

DIABLO HELIANTHELLA

Stems 1–5 dm, glabrous to coarsely hairy
Leaves: cauline few; petioles long; blades 2–6 cm wide, narrowly to widely elliptic
Inflorescence: head generally 1; peduncle 7–20 cm, stout, ± rough-hairy, often with 1–few bracts near tip; involucre 2.5–4 cm diam; outer phyllaries generally leaf-like, 3–10 cm, 7–20 mm wide, curving up around head; inner phyllaries 2–2.5 cm, coarsely ciliate
Ray flowers 13–21; ligules 1–3 cm
Disk flowers: corollas 6–7 mm, yellow; anthers yellow
Fruit 8–10 mm, obovate, glabrous; center thick; edges thin; pappus awns 0 or 2, < 1 mm
Chromosomes: 2n=30
Ecology: Open, grassy sites
Elevation: 200–1300 m.
Bioregional distribution: n San Francisco Bay Area
Horticultural information: In cultivation.