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Polygonum majus

WIRY KNOTWEED


Higher Taxonomy
Family: PolygonaceaeView DescriptionDichotomous Key
Common Name: BUCKWHEAT FAMILY
Habit: Annual to shrub [tree]. Stem: nodes swollen or not. Leaf: simple, basal or cauline, generally alternate; ocreae present or 0, generally scarious, persistent or not. Inflorescence: flower clusters in axillary to terminal cyme-, panicle-, raceme-, spike-, umbel- or head-like arrangements, entire inflorescence or main inflorescence branches generally subtended by bracts ("inflorescence bracts"); peduncles present or 0; flower clusters in Eriogoneae-Eriogonoideae subtended by involucre of >= 1 free or +- fused, sometimes awn-tipped bracts ("involucre bracts") or, in Polygonoideae and rarely in Eriogonoideae, not (if bracts completely fused, involucre "tubular"); pedicels in Eriogoneae each often subtended by 2 free, transparent, linear bractlets or in Polygonoideae all subtended by 2+ fused, membranous, wide bractlets. Flower: generally bisexual, small, 1--200 per node; perianth parts 2--6, generally in 2 whorls, free or basally fused, generally petal-like, often +- concave adaxially, often darker at midvein, often turning +- red or +- brown in age; stamens [1]3 or 6--9 in 2 whorls; ovary superior, 1-chambered, ovule 1, styles 1--3. Fruit: achenes, included in or exserted from perianth, generally 3-angled, ovoid or elliptic, generally glabrous.
Genera In Family: 48 genera, +- 1200 species: worldwide, especially northern temperate; some cultivated for food (Coccoloba, sea-grape; Fagopyrum, Rheum, Rumex) or ornamental (Antigonon, lovechain; Coccoloba; Muehlenbeckia; Persicaria; Polygonum), a few timbered (Coccoloba; Triplaris). Several (Emex; Fallopia; Persicaria; Polygonum; Rumex) are weeds. Note: Treatment of genera in Eriogonoideae based on monographic work of James L. Reveal. Involucre number throughout is number (1--many) per ultimate grouping, at tips of ultimate branches; flower number is per flower cluster or involucre, unless otherwise stated. Fagopyrum esculentum Moench not naturalized, considered an historical waif (or garden weed +- presently), therefore not treated.
eFlora Treatment Author: Mihai Costea, except as noted
Scientific Editor: Thomas J. Rosatti, Bruce G. Baldwin.
Genus: PolygonumView DescriptionDichotomous Key


Common Name: KNOTWEED
Habit: Annual, perennial herb to shrub. Stem: prostrate to erect, 8--16-ribbed or 4--5-angled with ribs 0 or obscure; glabrous or papillate-scabrous. Leaf: cauline, alternate, petioled or not; ocrea generally jointed to leaf, generally cylindric proximally, generally translucent distally, white or silvery, 2-lobed, glabrous, disintegrating to fibers or completely; blade linear, lanceolate, elliptic, ovate, or subround, entire. Inflorescence: axillary, terminal, generally spike-like; peduncle 0; pedicels present or 0, included in to exserted from bractlets; flowers 1--7(10). Flower: bisexual, base not stalk-like; perianth not enlarging, bell- to urn-shaped, glabrous, white or green-white to pink; perianth parts 5, fused 3--60[70]%, petal- or sepal-like, similar [or not], outer +- keeled or not, < to > inner, midveins generally a different shade or color than rest of perianth; stamens 3--8 (some staminodes or not), filaments or at least innermost free, wider at base, fused to perianth tube or not, anthers elliptic to oblong, white-yellow or generally pink to purple (orange-pink); styles (2)3, generally spreading, free or fused basally, stigmas 2--3, head-like. Fruit: included or exserted, wings 0, angles (2)3, 1 face much narrower than other (1)2 or not; tip beak-like, yellow-green, brown, or black. Seed: embryo curved.
Etymology: (Greek: poly, many, gony, knee joint, or gone, seed, of uncertain meaning) Note: Many species of sect. Polygonum with 2 kinds of fruit, differing in germination and morphology (summer fruit brown, ovate, tubercled to smooth; late-season fruit olive-green, lanceolate, smooth, 2--5 × > summer), but of little taxonomic importance. Mature, early-season plants with leaves, flowers, fruits needed for identification. Flowers "closed" or "1/2-open" should be determined on herbarium specimens. Other taxa in TJM (1993) moved to Aconogonon, Bistorta, Fallopia, Persicaria.
eFlora Treatment Author: Mihai Costea
Reference: Costea 2005 Brittonia 57:1--27
Polygonum majus (Meisn.) Piper
NATIVE
Habit: Annual. Stem: erect, 15--60 cm, +- wiry, generally papillate-scabrous, green, +- angled, branches 0 or not. Leaf: basal leaves often early-deciduous; ocreae 5--12 mm, glabrous or papillate-scabrous, proximally cylindric, distally torn or disintegrating to fibers; petiole 0--2 mm; blade 15--70 mm, 2--8 mm wide, lance-linear to narrowly oblong or lanceolate, margin rolled under, papillate-fine-dentate, tip acute or mucronate. Inflorescence: axillary, terminal, spike-like; pedicels exserted, reflexed, 0.5--1 mm; flowers 2--5. Flower: open or 1/2-open; perianth (3.5)4--5 mm, white or pink, tube 9--17% of length, lobes overlapped, oblong to oblong-obovate, +- keeled in distal 1/4, tips rounded, hood-shaped, midvein branches 0 or short; stamens 8. Fruit: included, 3.5--5 mm, elliptic, black, shiny or dull, smooth to striate-tubercled.
Ecology: Dry plains, meadows, serpentine or not; Elevation: 500--2000 m. Bioregional Distribution: KR, NCoR, CaR, SN, SnBr, w MP; Distribution Outside California: to British Columbia, Idaho. Flowering Time: Jun--Sep
Synonyms: Polygonum douglasii subsp. majus (Meisn.) J.C. Hickman
Jepson eFlora Author: Mihai Costea
Reference: Costea 2005 Brittonia 57:1--27
Index of California Plant Names (ICPN; linked via the Jepson Online Interchange)

Previous taxon: Polygonum hickmanii
Next taxon: Polygonum marinense

Botanical illustration including Polygonum majusbotanical illustration including Polygonum majus


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Citation for this treatment: Mihai Costea 2012, Polygonum majus, in Jepson Flora Project (eds.) Jepson eFlora, https://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=39209, accessed on November 08, 2024.

Citation for the whole project: Jepson Flora Project (eds.) 2024, Jepson eFlora, https://ucjeps.berkeley.edu/eflora/, accessed on November 08, 2024.

Polygonum majus
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©2008 Keir Morse
Polygonum majus
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©2008 Keir Morse
Polygonum majus
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©2008 Keir Morse
Polygonum majus
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©2009 Neal Kramer
Polygonum majus
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©2009 Neal Kramer

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Geographic subdivisions for Polygonum majus:
KR, NCoR, CaR, SN, SnBr, w MP
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map of distribution 1

(Note: any qualifiers in the taxon distribution description, such as 'northern', 'southern', 'adjacent' etc., are not reflected in the map above, and in some cases indication of a taxon in a subdivision is based on a single collection or author-verified occurrence).






 

Data provided by the participants of the  Consortium of California Herbaria.

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CCH collections by month Flowering-Fruiting Monthly Counts

Duplicates counted once; synonyms included.
Species do not include records of infraspecific taxa, if there are more than 1 infraspecific taxon in CA.
Blue line denotes eFlora flowering time (fruiting time in some monocot genera).