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Polygonum sawatchense subsp. oblivium

Higher Taxonomy
Family: PolygonaceaeView DescriptionDichotomous Key
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
Species: Polygonum sawatchenseView Description 

Habit: Annual. Stem: erect, 4--50 cm, glabrous or papillate-scabrous, green to +- brown, +- angled, branches 0 or from base. Leaf: ocreae 4--10 mm, glabrous or papillate-scabrous, proximally cylindric, distally disintegrating to fibers; petiole 0--2 mm; blade 8--45 mm, 2--8(12) mm wide, linear or narrowly oblong to oblanceolate, margin rolled under or flat, smooth or papillate-fine-dentate, tip acute, mucronate, rarely obtuse. Inflorescence: axillary, terminal, spike-like; pedicels included or exserted, erect, 1--4 mm; flowers 2--4. Flower: closed or at least some open; perianth (2.5)3--4 mm, +- green or +- red, flushed purple or not, margin white or pink, tube 20--40% of length, lobes overlapped, oblong or oblong-elliptic, +- keeled, tip rounded, hood-shaped, midvein branches 0 or few, at base; stamens 3--8. Fruit: included, 2.5--3.3 mm, elliptic or ovate, black, shiny, smooth.

Polygonum sawatchense Small subsp. oblivium Costea & Tardif
Stem: 5--15(25) cm, papillate-scabrous, green, branches 0 or few. Leaf: persistent, gradually reduced distally on stem; ocreae papillate-scabrous; blade 8--20(25) mm, 5--10 mm wide, elliptic to oblong-elliptic, margin flat, papillate-fine-dentate. Inflorescence: generally axillary, if also terminal then < 5 cm; pedicels 1--3 mm; flowers 1--3(4). Flower: at least some open; perianth 3--4 mm, green-white or -yellow, flushed with purple or not, margin white, tube 20--30% of length; stamens 8. Fruit: 2.6--3.3 mm, elliptic to elliptic-ovate.
Ecology: Dry, moist meadows, pastures, forest, sandy, gravelly, rocky substrates; Elevation: 1000--3100 m. Bioregional Distribution: NW, CaRH, n&c SNH, Wrn; Distribution Outside California: to British Columbia. Flowering Time: Jun--Aug
Jepson eFlora Author: Mihai Costea
Reference: Costea 2005 Brittonia 57:1--27
Index of California Plant Names (ICPN; linked via the Jepson Online Interchange)

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Citation for this treatment: Mihai Costea 2012, Polygonum sawatchense subsp. oblivium, in Jepson Flora Project (eds.) Jepson eFlora,, accessed on January 29, 2023.

Citation for the whole project: Jepson Flora Project (eds.) 2023, Jepson eFlora,, accessed on January 29, 2023.

Polygonum sawatchense subsp. oblivium
click for enlargement
© 2019 Neal Kramer
Polygonum sawatchense subsp. oblivium
click for enlargement
© 2009 Barry Breckling
Polygonum sawatchense subsp. oblivium
click for enlargement
© 2019 Neal Kramer
Polygonum sawatchense subsp. oblivium
click for enlargement
© 2009 Barry Breckling
Polygonum sawatchense subsp. oblivium
click for enlargement
© 2019 Neal Kramer
Polygonum sawatchense subsp. oblivium
click for enlargement
© 2019 Neal Kramer

More photos of Polygonum sawatchense subsp. oblivium in CalPhotos

Geographic subdivisions for Polygonum sawatchense subsp. oblivium:
NW, CaRH, n&c SNH, Wrn
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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 occurence).


Data provided by the participants of the  Consortium of California Herbaria.
View all CCH records
All markers link to CCH specimen records. The original determination is shown in the popup window.
Blue markers indicate specimens that map to one of the expected Jepson geographic subdivisions (see left map). Purple markers indicate specimens collected from a garden, greenhouse, or other non-wild location.
Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues.

CCH collections by month

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).