Jepson Flora Project: Jepson Interchange    

link to manual TREATMENT FROM THE JEPSON MANUAL (1993) previous taxon | next taxon
Jepson Interchange (more information)
©Copyright 1993 by the Regents of the University of California
For up-to-date information about California vascular plants, visit the Jepson eFlora.



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.



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.


P. douglasii Greene

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.


subsp. douglasii

Stem decumbent at high elevation, 3–80 cm
Leaves often falling before flowers appear, < 8 cm, linear to oblanceolate, abruptly reduced to scale-like bracts
Inflorescence spike-like, open
Flower: perianth 3–4 mm, generally closed (< 2.5 mm if open)
Fruit 3–4 mm, reflexed; enfolding perianth with a minute, curved stalk at base
Ecology: Common. Drying places
Elevation: 1000–3000 m.
Bioregional distribution: California
Distribution outside California: to Canada, e N.America
Flowering time: Jun–Sep
Synonyms: var. latifolium (Engelm.) Greene

previous taxon | next taxon
bioregional map for POLYGONUM%20douglasii%20subsp.%20douglasii being generated
YOU CAN HELP US make sure that our distributional information is correct and current. If you know that a plant occurs in a wild, reproducing state in a Jepson bioregion NOT highlighted on the map, please contact us with that information. Please realize that we cannot incorporate range extensions without access to a voucher specimen, which should (ultimately) be deposited in an herbarium. You can send the pressed, dried collection (with complete locality information indicated) to us (e-mail us for details) or refer us to an accessioned herbarium specimen. Non-occurrence of a plant in an indicated area is difficult to document, but we will especially value your input on those types of possible errors (see automatic conversion of distribution data to maps).

Retrieve Jepson Interchange Index to Plant Names entry for Polygonum douglasii subsp. douglasii
Retrieve dichotomous key for Polygonum
Overlay Consortium of California Herbaria specimen data by county on this map
Show other taxa with the same California distribution | Read about bioregions | Get lists of plants in a bioregion
Return to the Jepson Interchange main page
Return to treatment index page
  • This page is no longer being maintained.

University & Jepson Herbaria Home Page |
General Information | University Herbarium | Jepson Herbarium |
Visiting the Herbaria | On-line Resources | Research |
Education | Related Sites
Copyright © by the Regents of the University of California