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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.

THELESPERMA

Annual to perennial herb
Leaves opposite (or upper alternate)
Inflorescence: heads 1–few, generally discoid; involucre bell-shaped to hemispheric; phyllaries in 2 series, outer spreading, thick, free, inner erect, thin, ± fused; receptacle flat; chaff scales curved around disk flowers
Ray flowers 0–several, sterile; ligules yellow to red
Disk flowers generally many; corollas yellow to red, ± bilateral (inner lip 4-lobed), tube slender, throat widely cylindric; anther tips triangular; style tips triangular, minutely bristly
Fruit ± linear, ± compressed front-to-back, rounded, ± rough; pappus of 2 awns with reflexed barbs
Species in genus: 14 species: w North America, s South America
Etymology: (Greek: nipple seed, from rough fruits)

Introduced

T. megapotamicum (Spreng.) Kuntze

Perennial 3–6 dm, few-branched, glabrous, glaucous
Leaves 3–12 cm; lower 1–2-pinnately dissected, segments linear
Inflorescence: involucre 5–8 mm diam; inner phyllaries purplish, white-margined, ± = chaff scales
Ray flowers generally 0 (or ligules yellow, 5–6 mm)
Disk flowers: corollas 7.5–8.5 mm, yellow or orange
Fruit 4–8 mm, dark; pappus awns 1–2 mm, stout
Chromosomes: 2n=11,22
Ecology: Disturbed ground
Elevation: < 500 m.
Bioregional distribution: South Coast, s Channel Islands (Santa Catalina Island)
Distribution outside California: native Wyoming to Texas, S.America

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