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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 August 24, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html, accessed on August 24, 2016.


Persicaria lapathifolia
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© 2016 Keir Morse
Persicaria lapathifolia
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© 2016 Keir Morse
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
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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. Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues. Purple markers indicate specimens collected from a garden, greenhouse, or other non-wild location.
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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.