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. microthecum Nutt.

[Group 4] Subshrub or shrub 5–150 cm, 60–160 cm diam
Leaves cauline; lower ± clustered; blade 3–25 mm, generally ± oblanceolate, generally ± rolled under, tomentose (especially below)
Inflorescence cyme-like, generally ± flat-topped; bracts scale-like; involucres terminal, 1.5–4 mm
Flower: perianth 1.5–4 mm, white to rose or yellow, glabrous, stalk-like base 0
Fruit 1.5–3 mm, glabrous
Ecology: Dry places
Elevation: 1100–3300 m.
Bioregional distribution: Sierra Nevada, San Gabriel Mountains, San Bernardino Mountains, Great Basin Floristic Province, Mojave Desert
Distribution outside California: to Washington, Montana, Wyoming, Colorado, New Mexico
Reference: [Reveal 1971 Brigham Young Univ Sci Bull Biol Ser 13(1):1–45]
Highly variable; vars. intergrading, often indistinct, differentiated especially by geog.

Native

var. alpinum Reveal

Plant 4–10 cm
Leaf: blade 3–9 mm, oblanceolate, generally rolled under, thinly hairy above
Inflorescence: main branches generally < 1 cm
Flower: perianth white to rose
Ecology: Uncommon. Rocks
Elevation: 2500–3300 m.
Bioregional distribution: n High Sierra Nevada (Alpine Co.), n East of Sierra Nevada (Sweetwater Mtns).