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.

SENECIO

GROUNDSEL, RAGWORT, BUTTERWEED

Theodore M. Barkley

Annual to tree-like, generally ± loosely hairy, becoming ± subglabrous; roots generally fibrous, branched
Stems generally 1–few per rosette
Leaves alternate; lower generally petioled; middle generally weakly clasping; uppermost generally bract-like
Inflorescence often ± flat-topped; heads radiate or discoid, 1–many; involucre cylindric to hemispheric; main phyllaries in 1 equal series (often subtended by few, much-reduced outer phyllaries)
Ray flowers 0–13; ligules generally yellow to orange
Disk flowers generally < 40; corolla generally ± yellow; style tips truncate to obtuse, generally hair-tufted
Fruit cylindric; ribs shallow, often stiff-hairy; pappus of thin, minutely barbed deciduous bristles ± = fruit body
Species in genus: ± 1500 species: worldwide; some cultivated, some of unusual form
Recent taxonomic note: *For revised taxonomy of Senecio, see Barkley 1999 Sida 18(3):661–672.
Etymology: (Latin: old man, from white pappus)
Reference: [Barkley 1978 North America Flora II 10:50–139]
Among largest genera of flowering plants.

Native

S. integerrimus Nutt.

Biennial or perennial herb 2–7 dm, from button-like caudex; roots fleshy, unbranched
Leaves: lower petioled or tapered to base, 6–25 cm; blade generally lanceolate, subentire
Inflorescence: heads radiate, 6–20(30), central head often largest, peduncle shorter; main phyllaries ± 21, sometimes 13
Ray flowers (8)13; ligules 6–15 mm, yellow or off-white
Disk flowers 20–50
Fruit glabrous
Chromosomes: 2n=40,80
Ecology: Grassland, open forest
Elevation: 150–3600 m.
Bioregional distribution: Klamath Ranges, Inner North Coast Ranges, Cascade Range, Sierra Nevada, Great Basin Floristic Province
Distribution outside California: to sw Canada, north-central US, Colorado

Native

var. ochroleucus (A. Gray) Cronquist

Leaves: petiole often distinct
Inflorescence: main phyllaries < 10 mm, greenish or minutely black-tipped
Ray flowers present; ligules off-white to pale cream
Ecology: Coniferous forest
Elevation: 600–1700 m.
Bioregional distribution: Klamath Ranges
Distribution outside California: to British Columbia, Montana
Horticultural information: TRY.