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Jepson Interchange (more information)
©Copyright 1993 by the Regents of the University of California

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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. marinense T. Mert. & P.H. Raven

MARIN KNOTWEED

Annual
Stem prostrate to erect, < 4 dm, ± round; ribs obvious
Leaves generally 1–3 cm, ± sessile, gradually smaller upward; blade narrowly oblanceolate to elliptic
Inflorescence: flowers in axils of most leaves
Flower: perianth ± 3.5 mm, green, margin white
Fruit 3.5–4.5 mm, narrowly ovoid, olive-brown, very shiny, exserted
Chromosomes: 2n=60
Ecology: UNCOMMON. Coastal salt marshes
Elevation: < 10 m.
Bioregional distribution: San Francisco Bay Area (especially Marin Co.).Related to P. aviculare , taxonomic status uncertain: possibly = P. robertii Loisel.; if so, alien, native to w Medit. Endangered by salt marsh development. Merits immediate study.
See the CNPS Inventory for information about endangerment and rarity.
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