Jepson Flora Project: Jepson Interchange    

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Jepson Interchange (more information)
©Copyright 1993 by the Regents of the University of California

  • Up-to-date information about California vascular plants is available from the Jepson eFlora.



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.



Annual or perennial herb
Stems generally erect
Leaves opposite or alternate, generally reduced upward, often 3-veined from near base, generally rough-hairy
Inflorescence: heads radiate, solitary or in cymes; involucre bell-shaped to hemispheric; phyllaries in 1–3 generally ± equal series, free; receptacle flat to rounded; chaff scales 0–3-lobed
Ray flowers 10–many, sterile; ligules yellow
Disk flowers many; corollas yellow to red or purple, tube short, throat base often swollen, lobes triangular; style appendages triangular
Fruit oblanceolate to obovate, ± compressed; sides rounded; pappus generally of 2 deciduous, lanceolate to ovate scales (sometimes also 1–several shorter scales)
Species in genus: 67 species: Am
Etymology: (Greek: sun flower)
Reference: [Heiser 1969 Mem Torrey Bot Club 22(3):1–218]


H. annuus L.

Annual < 3 m
Stems ± rough-hairy
Leaves long-petioled; blade 10–40 cm, widely lanceolate to widely ovate, base generally ± cordate, tip obtuse to acute, margin serrate
Inflorescence: heads generally few–many; peduncles 2–20 cm; involucre 1.5–3(20) cm diam; phyllaries 15–25 mm, lanceolate to widely ovate, abruptly acuminate, glabrous to rough-hairy, generally ciliate; chaff scales deeply 3-lobed, middle lobe long-acuminate
Ray flowers 15–many; ligule generally > 2.5 cm
Disk flowers: corollas 5–8 mm, lobes red to purple or yellow
Fruit 3–15 mm; pappus scales 2–3.5 mm
Chromosomes: 2n=34
Ecology: Disturbed areas, scrub, many other habitats
Elevation: < 1900 m.
Bioregional distribution: California
Distribution outside California: to e N.America
Flowering time: Jul–Oct
Highly variable; hybridizes with several other species
Synonyms: subsp. jaegeri (Heiser) Heiser; subsp. lenticularis (Douglas) Cockerell; var. macrocarpus (DC.) Cockerell
Head 1, very large In cultivation forms
Horticultural information: SUN: 2, 3, 4, 5, 6, 17 &IRR: 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 18, 19, 20, 21, 22, 23, 24.

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