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Vascular Plants of California
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Persicaria hydropiperoides

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: 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.
Etymology: (Latin: persica, peach, aria, pertaining to; from resemblance of leaves of some species to those of peach)
eFlora Treatment Author: Mihai Costea
Persicaria hydropiperoides (Michx.) Small
Habit: Perennial herb, rhizomed. Stem: decumbent to ascending, 15--100 cm, glabrous or obscurely strigose distally. Leaf: ocrea 5--20 mm, cylindric, brown, margins truncate, ciliate, bristles (2)4--10 mm, surface glabrous or strigose, not gland-dotted; petiole 0.2--2 cm; blade 5--25 cm, 0.4--3.7 cm wide, linear- to widely lanceolate, glabrous or appressed-hairy on midveins, also on surfaces or not, generally abaxially gland-dotted, adaxial dark blotch 0, base tapered or acute, tip acuminate. Inflorescence: axillary, terminal, erect, generally uninterrupted, 30--80 mm, 2--5 mm wide; peduncle 10--30 mm, glabrous or strigose; bractlets overlapped distally, often not proximally; pedicels ascending, 1--1.5 mm; flowers 2--6. Flower: perianth (1.5) 2.5--4 mm, bell-shaped, +- enlarging, not gland-dotted, pink or white-+- green, lobes 5, obovate, veins prominent or not, not anchor-shaped, tips obtuse to rounded; stamens 8, included or exserted, anthers pink or red; styles 3, fused nearly 1/2. Fruit: included or exserted, 1.5--3 mm, 1--2.3 mm wide, 3-angled, brown to black, shiny, smooth. Chromosomes: 2n=40.
Ecology: Wet banks, shallow water, marshes, moist prairies; Elevation: < 1500 m. Bioregional Distribution: CA-FP, DSon; Distribution Outside California: to eastern North America, Mexico. Flowering Time: Jun--Oct Note: Confused with Persicaria maculosa (see key).
Synonyms: Polygonum hydropiperoides Michx.; Polygonum hydropiperoides var. asperifolia Stanford; Persicaria opelousana (Small) Small; Persicaria paludicola Small
Jepson eFlora Author: Mihai Costea
Index of California Plant Names (ICPN; linked via the Jepson Online Interchange)

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Botanical illustration including Persicaria hydropiperoides

botanical illustration including Persicaria hydropiperoides

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Citation for this treatment: Mihai Costea 2012, Persicaria hydropiperoides, in Jepson Flora Project (eds.) Jepson eFlora,, accessed on May 23, 2024.

Citation for the whole project: Jepson Flora Project (eds.) 2024, Jepson eFlora,, accessed on May 23, 2024.

Persicaria hydropiperoides
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©2010 Vernon Smith
Persicaria hydropiperoides
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©2016 Keir Morse
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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©2005 George W. Hartwell

More photos of Persicaria hydropiperoides
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Geographic subdivisions for Persicaria hydropiperoides:
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2. County and Jepson Region polygons can be turned off and on using the check boxes.
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).