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. saxatile S. Watson

[Group 3] Perennial 10–20(40) cm; mats 5–20 cm diam
Leaves clustered on low stems; blade 3–25 mm, elliptic to round, densely tomentose
Inflorescence cyme-like, ± stout, ± tomentose; involucres sessile (most lateral), 2–4 mm, ± tomentose, teeth 5–6
Flower: perianth 3–7 mm, white to rose or yellowish, glabrous, outer lobes narrower, stalk-like base long, sharply 3-angled, ± indistinct
Fruit 3.5–4 mm, glabrous, winged
Chromosomes: n=20
Ecology: Common. Decomposed granite or volcanic rocks
Elevation: 900–3400 m.
Bioregional distribution: s Sierra Nevada, Central Western California, Southwestern California, East of Sierra Nevada, Desert Mountains
Distribution outside California: s Nevada
Flowering time: May–Jul
Horticultural information: DRN, DRY, SUN: 1, 2, 3, 7, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24.