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

	The second edition of The Jepson Manual (2012) is available from the University of California Press
	See also the Jepson eFlora, which parallels the Second Edition

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. douglasii Greene

Annual
Stem generally erect, 3–80 cm, ± angled; ribs 0 or obscure
Leaf < 8 cm, sessile; blade linear, elliptic, or oblanceolate, smaller upward, vein 1
Inflorescence 5–20 cm, open or dense
Flower: perianth 2–5 mm, opening or not, pink or white, margins and midribs generally red or green; stamens generally 8(3–8, may vary within plant)
Fruit 2–5 mm, black, shiny
Chromosomes: 2n=40
Ecology: Common. Open, slopes, dry meadows
Elevation: < 3500 m.
Bioregional distribution: California (especially mtns, coast)
Distribution outside California: to Canada, e N.America
Variable intergrading complex; subspp. maintained in mixed populations merge over geog range. Generally self-pollinating. Homopteran insect parasites shorten stem, broaden leaves, enlarge and sterilize flowers in infected plants. Further study warranted.

Native

subsp. austiniae (Greene) E. Murray

Plant ± funnel-like in shape
Stem: branches ascending from base, generally < 20 cm; internodes ± equal
Leaves appearing ± basal and crowded, persistent, ± elliptic, ± sharply acute, abruptly reduced to scale-like bracts
Inflorescence spike-like, open
Flower: perianth ± 2 mm, closed
Fruit 2 mm, reflexed; enfolding perianth with a minute, curved stalk at base
Ecology: Uncommon. Sagebrush plains
Elevation: ± 1500 m.
Bioregional distribution: Modoc Plateau
Distribution outside California: to Oregon, Montana, Wyoming
Synonyms: var. a. (Greene) M.E. Jones