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.

POLYGONUM

KNOTWEED, SMARTWEED

Annual, perennial herb, shrub, vine
Stem prostrate to erect, or climbing, or floating, < 3 m
Leaves generally cauline, alternate, sessile or petioled; stipules fused, sheathing stem above nodes, generally scarious or membranous; blade sometimes obviously jointed to stipule sheath
Inflorescence: unit a 1–8-flowered cluster, these arrayed singly or in head-like to open panicles
Flower: perianth lobes generally 5; stamens 3–8, filaments generally wider at base
Fruit generally ovoid, 3-angled, sometimes round, flat, indented; shiny to dull, brown to black
Species in genus: ± 300 species: worldwide, especially n temp
Etymology: (Greek: many knees, from swollen nodes of some species)
Reference: [Ronse Decraene & Ackeroyd 1988 Bot J Linn Soc 98:321–371]
Segregate genera (e.g., Bistorta, Fallopia, Persicaria ) are sometimes recognized.

Native

P. bistortoides Pursh

WESTERN BISTORT

Perennial from short, bulb-like rhizome
Stem erect, unbranched, generally 20–70 cm
Leaves ± basal or reduced rapidly upward, generally 15–40 cm, petioled; blade oblong or strap-shaped to narrowly lanceolate, leathery, ± glaucous, especially below
Inflorescence long peduncled, dense, ± oblong
Flower: perianth 4–5 mm, white or pink, lobes nearly free; stamens exserted, filaments thread-like
Fruit 3–4.5 mm, ± obovoid, brown, shiny
Ecology: Common. Wet mtn meadows
Elevation: 1500–3000 m.
Bioregional distribution: California Floristic Province, n East of Sierra Nevada (uncommon in coastal freshwater marshes 0–20 m. North Coast, San Francisco Bay Area)
Distribution outside California: to Alaska, e N.America
Flowering time: Jun–Aug
Variable
Horticultural information: WET, SUN: 1, 2, 3, 4, 5, 6, 7, 15, 16, 17, 18; INV.