TREATMENT FROM THE JEPSON MANUAL (1993)	previous taxon | next taxon Jepson Interchange (more information)
	©Copyright 1993 by the Regents of the University of California

POLYGONACEAE

BUCKWHEAT FAMILY

James C. Hickman

Annual to trees, some dioecious
Stem: nodes often swollen
Leaves simple, basal or cauline, alternate, opposite, or whorled, generally entire; stipules 0 or obvious and fused into a generally scarious sheath around stem
Inflorescence: small cluster, axillary or arrayed in cymes or panicles; involucres sometimes subtending 1–many flowers
Flower generally bisexual, small, ± radial; perianth generally 5–6-lobed, base ± tapered, often jointed to pedicel; stamens 2–9, often in 2 whorls; ovary superior, styles generally 3, generally fused at base
Fruit: achene, generally enclosed by persistent perianth, generally 3-angled, ovoid, and glabrous
Genera in family: 50 genera, 1100 species: worldwide, especially n temp; some cultivated for food (Fagopyrum ; Rheum , rhubarb; Rumex , sorrel) or ornamental (Antigonon , coral-vine; Muehlenbeckia ; Polygonum )
Reference: [Ronse Decraene & Akeroyd 1988 Bot J Linn Soc 98:321–371; Reveal et al. 1989 Phytologia 66(2–4):83–414]
Treatments of the 15 eriogonoid genera are based on the monographic work of James L. Reveal, who is gratefully acknowledged.

CENTROSTEGIA

Species in genus: 1 sp
Etymology: (Greek: spurred cover, from involucre)
Reference: [Reveal 1989 Phytologia 66:199–220]

Native

C. thurberi Benth.

THURBER'S SPINEFLOWER

Annual, spreading, 3–30 cm, glandular
Leaves basal; stipule 0; ± petioled; blade 5–40 mm, oblanceolate, glabrous
Inflorescence 6–50 cm diam; bract 1 per node, 1–10 mm, 3-lobed, awns 1–2 mm; involucre 1 per node, sessile, 2–8 mm, cylindric above, swollen at base, upper awns 5, < 1 mm, basal awns 3, < 2 mm, curved; flowers 2 per involucre
Flower: perianth 2–3.5 mm, white to pink, hairy, lobes 6; stamens 9
Fruit 2–2.5 mm, brown
Chromosomes: n=19
Ecology: Common. Desert scrub, other dry sandy places
Elevation: 300–2400 m.
Bioregional distribution: s San Joaquin Valley, e Inner South Coast Ranges, Transverse Ranges, East of Sierra Nevada, Desert
Distribution outside California: to Nevada, Utah, Arizona, nw Mexico
Flowering time: Apr–Jun
Synonyms: Chorizanthe t. (Benth.) S. Watson