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Persicaria hydropiper

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
Genus: PersicariaView DescriptionDichotomous Key

Common Name: SMARTWEED
Habit: Annual, perennial herb, rhizomed or stoloned. Stem: prostrate to erect, ribbed or +- so or not, glabrous or hairy, generally with adventitious roots. Leaf: cauline, alternate, petioled or not; ocrea papery, rarely +- leaf-like, opaque, persistent or disintegrating, glabrous to variously hairy; blade lanceolate or ovate to hastate or sagittate, entire. Inflorescence: axillary, terminal, generally spike-like; flowers 1--14; peduncle present, pedicels present [or 0]. Flower: bisexual or functionally +- unisexual, base not stalk-like; perianth not or +- enlarging, bell-shaped (urn-shaped, rotate), glabrous, gland-dotted or not, green-white, white, pink, or red; perianth parts 4--5, fused 1/4--2/3, outer 2 > inner 2 or 3; stamens 5--8, filaments free, cylindric, thread-like, glabrous, outer fused to perianth tube or not, anthers elliptic to ovate, yellow, pink, or red; styles 2--3, erect to reflexed, free or fused, stigmas head-like. Fruit: included or exserted, brown or dark-brown to black, not winged, discoid, lens-shaped, or 3-angled. Seed: embryo curved.
Species In Genus: +- 100 species: +- worldwide. Etymology: (Latin: persica, peach, aria, pertaining to; from resemblance of leaves of some species to those of peach)

Persicaria hydropiper (L.) Delarbre
Habit: Annual, rhizomes, stolons 0. Stem: ascending to erect, 20--60(100) cm, gland-dotted. Leaf: ocrea 8--15 mm, brown, cylindric or funnel-shaped, margins truncate, ciliate, bristles 1--4 mm, surface glabrous or strigose, generally gland-dotted; petiole 0--0.8 cm; blade (1.5)4--10(15) cm, 0.4--2.5 cm wide, lanceolate to narrowly diamond-shaped, glabrous or scabrous on midveins, +- gland-dotted, adaxial dark blotch 0, base wedge-shaped, tip acute to acuminate. Inflorescence: axillary, terminal, erect or nodding, interrupted or not distally, 30--180 mm, 5--9 mm wide; peduncle (0)10--50 mm, glabrous, gland-dotted; bractlets not overlapped; pedicels ascending, 1--3 mm; flowers 1--3(5). Flower: perianth 2--3.5 mm, +- bell-shaped, gland-dotted, green-white or pink, lobes 4--5, obovate, margins +- red, veins +- prominent, not anchor-shaped, tips obtuse to rounded; stamens 6--8, included, anthers pink or red; styles 2--3, fused basally. Fruit: included or exserted, 2--3 mm, 1.5--2 mm wide, lens-shaped or 3-angled, brown-black, dull, minutely rough. Chromosomes: 2n=20.
Ecology: Shores of lakes, ponds, riverbanks, forested wetlands, pastures, disturbed ground; Elevation: < 1500 m. Bioregional Distribution: n&c CA-FP; Distribution Outside California: to northern and eastern North America, also Asia, Africa, Australia; native to Europe. Flowering Time: May--Dec
Synonyms: Polygonum hydropiper L.
eFlora Treatment Author: Mihai Costea
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Citation for this treatment: Mihai Costea 2016. Persicaria hydropiper, in Jepson Flora Project (eds.) Jepson eFlora,, accessed on May 05, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora,, accessed on May 05, 2016.

Persicaria hydropiperoides
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© 2005 George W. Hartwell
Persicaria hydropiperoides
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© 2015 Barry Breckling
Persicaria hydropiperoides
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© 2015 Barry Breckling
Persicaria hydropiperoides
click for enlargement
© 2005 George W. Hartwell

More photos of Persicaria hydropiper in CalPhotos

Geographic subdivisions for Persicaria hydropiper:
n&c CA-FP;
Markers link to CCH specimen records. If the markers are obscured, reload the page [or change window size and reload]. Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues.
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).

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Data provided by the participants of the Consortium of California Herbaria.
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CCH collections by month

Duplicates counted once; synonyms included.
Species do not include records of infraspecific taxa.
Blue line denotes eFlora flowering time.