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Jepson Interchange (more information)
©Copyright 1993 by the Regents of the University of California
For up-to-date information about California vascular plants, visit the Jepson eFlora.

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.

ERIOGONUM

WILD BUCKWHEAT

Annual to shrub
Leaves generally ± basal (clustered on low stems or cauline), petioled, generally ± tomentose below (often shedding above); stipule 0
Inflorescence openly cyme-like, umbel-like, or head-like, generally ± scapose; bracts (any whorled, leaf-like structures on inflorescence) 3–many per node, leaf-like to scale-like; involucres generally 1 per node, generally ± obconic, lobes (or short teeth) generally 3–10, generally erect; flowers generally many per involucre, pedicelled
Flower: perianth white, yellow, or red, lobes 6, generally ± oblong to obovate; stamens 9
Fruit brown to black, glabrous to hairy
Species in genus: ± 250 species: North America
Etymology: (Greek: woolly knees, from hairy nodes of some)
Reference: [Reveal 1989 Phytologia 66:295–414]
Largest dicot genus in CA; apparently currently differentiating; many taxa ± indistinct. Better habitat data needed. Many are excellent bee fodder
Horticultural information: Most are attractive and easy to grow with good drainage.

Native

E. umbellatum Torr.

SULFUR FLOWER

[Group 3] Perennial to shrub, 10–200 cm, 10–200 cm diam
Leaves clustered on low stems; blade 3–40 mm, generally ± elliptic, generally densely tomentose (especially below)
Inflorescence umbel- to head-like, erect, slender; bracts leaf-like, subtending rays (if ray 1, appearing whorled near mid-axis), rarely alternate on main axis); involucre generally 1 per ray, 1–6 mm, ± tomentose, lobes 6–12, long, reflexed
Flower: perianth 2.5–12 mm, generally ± yellow becoming reddish (cream to purple), glabrous, lobes ± obovate, stalk-like base long, distinct
Fruit 2–5 mm, glabrous
Ecology: Abundant. Dry, open, often rocky places
Elevation: 200–3700 m.
Bioregional distribution: California (except North Coast, Great Central Valley, Central Coast, South Coast, Channel Islands, Sonoran Desert)
Distribution outside California: to w Canada, Colorado, New Mexico
Extremely variable and difficult. Many vars. intergrade, best dispositions unclear; more study needed.

Native

var. covillei (Small) Munz & Reveal

Low mat
Leaf: blade 2–6 mm wide, ± narrowly elliptic, sometimes remaining densely tomentose above
Inflorescence simple, generally spreading
Flower: perianth 2–5 mm, bright yellow
Ecology: Uncommon. Subalpine rocks
Elevation: 2600–3600 m.
Bioregional distribution: c&s High Sierra Nevada (especially Tulare, Inyo cos.), White and Inyo Mountains
Flowering time: Jul–Sep
Intergrades with var. nevadense.

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bioregional map for ERIOGONUM%20umbellatum%20var.%20covillei being generated
 
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Retrieve Jepson Interchange Index to Plant Names entry for Eriogonum umbellatum var. covillei
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