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Persicaria lapathifolia
WILLOW WEED

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
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 lapathifolia (L.) Delarbre
NATIVE
Habit: Annual; rhizomes, stolons 0. Stem: ascending to erect, 10--100 cm, glabrous to appressed-hairy distally, gland-dotted or not. Leaf: ocrea 4--25(35) mm, cylindric, brown, margins truncate, glabrous or ciliate, bristles 0 or < 1 mm, surface glabrous (strigose), not gland-dotted; petiole 0--1.5 cm; blade 4--12(22) cm, (0.3)0.5--4(6) cm wide, narrowly to widely lanceolate, strigose on main veins, glabrous or tomentose, gland-dotted abaxially, dark-blotched or not adaxially, base +- wedge-shaped, tip acuminate. Inflorescence: axillary, terminal, generally +- nodding, uninterrupted, 30--80 mm, 5--12 mm wide; peduncle 2--25 mm, glands +- stalked; bractlets generally overlapped; pedicels ascending, 0.5--2.3 mm; flowers 4--13. Flower: perianth 3--4 mm, bell-shaped, +- enlarging, not gland-dotted, green-white to pink, lobes 4(5), obovate to elliptic, veins prominent, those of outer parts 2-branched distally, anchor-shaped, tips obtuse to rounded; stamens 5--6, included, anthers pink or red; styles 2(3), fused basally. Fruit: included or exserted, 1.5--3.2 mm, 1.6--3 mm wide, generally lens-shaped (< 1% 3-angled), brown to black, shiny or dull, smooth. Chromosomes: 2n=22.
Ecology: Moist places, disturbed areas, roadsides, fields; Elevation: < 1500 m. Bioregional Distribution: CA; Distribution Outside California: North America, South America, Europe, Asia, Africa. Flowering Time: Jun--Oct Note: Highly variable, > 20 infraspecific taxa named but not worthy of taxonomic recognition.
Synonyms: Polygonum lapathifolium L.; Polygonum lapathifolium var. salicifolium Sibth.; Polygonum scabrum Moench
eFlora Treatment Author: Mihai Costea
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Citation for this treatment: Mihai Costea 2016. Persicaria lapathifolia, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=37292, accessed on May 05, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html, accessed on May 05, 2016.


Persicaria lapathifolia
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© 2013 Neal Kramer
Persicaria lapathifolia
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© 2013 Neal Kramer
Persicaria lapathifolia
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© 2003 George W. Hartwell
Persicaria lapathifolia
click for enlargement
© 2013 Neal Kramer
Persicaria lapathifolia
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© 2013 Neal Kramer
Persicaria lapathifolia
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© 2013 Neal Kramer

More photos of Persicaria lapathifolia in CalPhotos


Geographic subdivisions for Persicaria lapathifolia:
CA;
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.
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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).

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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.