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

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.

LACTUCA

LETTUCE

G. Ledyard Stebbins

Annual to perennial herb; sap milky
Stems erect, 0.5–1.5+ m
Leaves basal and cauline, alternate, entire to pinnately lobed
Inflorescence: heads ligulate, many, in panicles; involucre cylindric; phyllaries in 2–several series; receptacle naked
Flowers few–many; ligules yellow or cream to blue, readily withering
Fruit flattened, short- or long-beaked; pappus of many bristles, falling separately
Species in genus: ± 100 species: ± worldwide temp
Etymology: (Latin: milky)

Introduced

L. canadensis L.

Mostly biennial from taproot, 0.5–2.5 m
Leaves many, elliptic in outline, lobed; lobes linear, curved, mostly entire; bases acute, clasping
Inflorescence open, heads in flower 5–10 mm wide; involucre in fruit 10–15 mm
Flowers 13–25; corolla pale yellow
Fruit 5–6 mm, elliptic, blackish, rough, with 1 rib on each face, unwinged; beak pale, ± = body; pappus 5–7 mm, white
Chromosomes: 2n=34
Ecology: Forests and waste places
Elevation: < 1050 m.
Bioregional distribution: Klamath Ranges, n Sierra Nevada
Distribution outside California: native to e N.America

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bioregional map for LACTUCA%20canadensis being generated
 


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