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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.

MICROPUS

James D. Morefield

Annual, generally grayish, cobwebby to tomentose
Stems 1–several, erect; central axis dominant
Leaves simple, alternate (ours), ± sessile, narrowly oblanceolate to elliptic (ours), entire
Inflorescence: heads disciform, ± sessile, solitary or in groups of 2–5; bracts like leaves; phyllaries 4–6, equal, obovate, rounded, scarious, persistent; receptacle chaffy; chaff scales subtending the pistillate flowers (pistillate chaff) > phyllaries, each enclosing a flower, falling with a fruit, bulged out and up, ± compressed side-to-side, ± thickened, hard (at least in part), ± woolly, tip ± offset to inner edge, scarious-winged; chaff scales subtending disk flowers (disk chaff) 0 or reduced, open or folded, glabrous, scarious
Pistillate flowers 4–8(12) in 1(2) series; corollas tubular
Disk flowers staminate, 2–5; ovary vestigial
Fruit obovate, bulged out and up, compressed side-to-side, smooth; style ± offset to inner edge; pappus 0; disk pappus 0 or of 1–5 smooth, deciduous bristles, included
Species in genus: 5 species: CA-FP, Medit
Etymology: (Greek: small foot)
Reference: [Holub 1976 Flora Europaea 4:126]
Ongoing research may show CA species fit best in Eur Bombycilaena , a conclusion compatible with this generic description.

Native

M. californicus Fisch. & C.A. Mey.

SLENDER COTTONWEED


Inflorescence: heads 2–4 mm, depressed; receptacle not > wide; pistillate chaff scales 2–4 mm, thickened and hard throughout, tip projected upward from inner edge of scale, ± cylindric, beak-like, wing obscure, ± linear, withering; disk chaff 0
Pistillate flowers 4–6 in 1 series
Disk flowers 1–2 mm, 5-lobed
Fruit 1.4–2.6 mm; pappus bristles of disk fruit 0 or 1, 0.9–1.5 mm
Ecology: Dry or moist, bare or grassy places
Elevation: < 1700 m.
Bioregional distribution: California Floristic Province
Distribution outside California: w Oregon, nw Baja California

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bioregional map for MICROPUS%20californicus being generated
 
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Retrieve Jepson Interchange Index to Plant Names entry for Micropus californicus
Retrieve dichotomous key for Micropus
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Overlay Consortium of California Herbaria specimen data by county on this map
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