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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.

MACHAERANTHERA

David J. Keil and Gregory K. Brown

Annual to subshrubs
Stems from taproot or ± branched caudex
Leaves simple, alternate, entire to pinnately dissected; teeth or lobes often ± bristle-tipped
Inflorescence: heads radiate or discoid, solitary or cymosely clustered; involucre bell-shaped, hemispheric, or obconic; phyllaries in 2–several series of unequal length, basal portion straw-colored to purplish, tips green; receptacle convex, naked or with short, triangular scales (not chaff)
Ray flowers 8–many; corollas yellow, white, pink, blue, or purple
Disk flowers 10–many; corollas yellow; style tips triangular to linear, acute
Fruit linear to club-shaped or obovoid, smooth or several–many-ribbed, glabrous to densely hairy; pappus of many unequal bristles (ray pappus sometimes 0)
Species in genus: ± 35 species: temp w North America
Etymology: (Greek: sword-like anthers)
Reference: [Hartman 1990 Phytologia 68:439–465]

Native

M. asteroides (Torr.) Greene

Biennial, perennial herb < 10 dm, generally canescent-puberulent and nonglandular
Stems 1–several from base, generally branched above and ± bushy
Leaves generally 3–10 cm, generally 5–25 mm wide, lanceolate to oblanceolate, irregularly dentate to minutely serrate or subentire; lower tapered; upper clasping
Inflorescence: heads radiate; phyllaries generally in 5–12 series, tips short-triangular to elongate, acuminate, spreading to bent backward, puberulent
Ray flowers many; corollas blue-purple; ligules 1–2 cm
Disk flowers many; corollas 5.5–8 mm
Fruit 2.5–3.5 mm, narrowly obovate, weakly curved and ± flattened with 5–7 ribs on each face, glabrous or ± silky; pappus 6–8 mm
Ecology: Chaparral, woodland, scrub; ± 100 m
Elevation: 800–2400 m.
Bioregional distribution: Peninsular Ranges, Sonoran Desert
Distribution outside California: to s Nevada, sw New Mexico, n Mexico
Perhaps not a different sp. from M. canescens.

Native

var. asteroides


Leaves: middle cauline leaves 6–15(25) mm wide, minutely serrate
Inflorescence: involucre hemispheric; phyllary tips 3–6 mm, narrowly acuminate
Chromosomes: 2n=8
Ecology: scrub
Elevation: ± 100 m.
Bioregional distribution: e Sonoran Desert (near Colorado River)
Distribution outside California: to sw New Mexico, n Mexico

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