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Pennsylvania smartweed, pinkweed, renouée de pennsylvanie

Habit Plants annual, 1–20 dm; roots also occasionally arising from basal nodes; rhizomes and stolons absent.
Stems

ascending to erect, simple or branched, ribbed, glabrous or appressed-pubescent distally, eglandular or stipitate-glandular distally.

Leaves

ocrea brownish, cylindric, 5–20 mm, chartaceous, base inflated, margins truncate, eciliate or ciliate with bristles to 0.5 mm, surface glabrous or appressed-pubescent, eglandular;

petiole 0.1–2(–3) cm, glabrous or appressed-pubescent;

blade sometimes with dark triangular or lunate blotch adaxially, narrowly to broadly lanceolate, 4–17(–23) × (0.5–)1–4.8 cm, base tapered to cuneate, margins antrorsely scabrous, apex acuminate, faces glabrous or appressed-pubescent, eglandular or glandular-punctate abaxially and occasionally adaxially.

Inflorescences

terminal and axillary, erect or rarely nodding, uninterrupted, 5–50 × 5–15 mm;

peduncle 10–55(–70) mm, glabrous or pubescent, usually stipitate-glandular;

ocreolae overlapping, margins eciliate or ciliate with bristles to 0.5 mm.

Pedicels

ascending, 1.5–4.5 mm.

Flowers

2–14 per ocreate fascicle, homostylous;

perianth greenish white to roseate, glabrous, not glandular-punctate, accrescent;

tepals 5, connate ca. 1/4–1/3 their length, obovate to elliptic, 2.5–5 mm, veins prominent, not anchor-shaped, margins entire, apex obtuse to rounded;

stamens 6–8, included;

anthers yellow, pink, or red, elliptic;

styles 2(–3), connate at bases.

Achenes

included or apex exserted, brown to black, discoid or, rarely, 3-gonous, without central hump on 1 side, 2.1–3.4 × 1.8–3 mm, shiny, smooth.

2n

= 88.

Persicaria pensylvanica

Phenology Flowering May–Dec.
Habitat Moist, disturbed places, ditches, riverbanks, cultivated fields, shorelines of ponds and reservoirs
Elevation 0-1800 m (0-5900 ft)
Distribution
from FNA
AK; AL; AR; AZ; CA; CO; CT; DC; DE; FL; GA; IA; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; ND; NE; NH; NJ; NM; NV; NY; OH; OK; PA; RI; SC; SD; TN; TX; UT; VA; VT; WI; WV; WY; NB; NF; NS; ON; QC; South America (Ecuador); Europe (England, Spain)
[WildflowerSearch map]
[BONAP county map]
Discussion

Persicaria pensylvanica is a morphologically variable allotetraploid, with P. lapathifolia probably one of the parents (L. L. Consaul et al. 1991). Three or four varieties (under Polygonum) often have been accepted in North American floras; the characters on which these are based vary greatly within and among populations. J. W. Taylor-Lehman (1987) concluded that Polygonum pensylvanicum is best treated as a polymorphic species without infraspecific taxa, based on specimens primarily from Ohio. The heterostylous Persicaria bicornis often is included in P. pensylvanica. A single chromosome count of 2n = 22 reported by Á. Löve and D. Löve (1982), which could not be confirmed by Consaul et al. because the voucher could not be found, is excluded. Flowers with three styles and trigonous achenes are produced; they are exceedingly rare and probably mostly overlooked. Several Native American tribes prepared infusions and decoctions from P. pensylvanica, which they used as drugs for humans and horses (D. E. Moerman 1998).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 5, p. 588.
Parent taxa Polygonaceae > subfam. Polygonoideae > Persicaria > sect. Persicaria
Sibling taxa
P. amphibia, P. arifolia, P. bicornis, P. bungeana, P. capitata, P. careyi, P. chinensis, P. glabra, P. hirsuta, P. hydropiper, P. hydropiperoides, P. lapathifolia, P. longiseta, P. maculosa, P. meisneriana, P. minor, P. nepalensis, P. orientalis, P. perfoliata, P. punctata, P. robustior, P. sagittata, P. setacea, P. virginiana, P. wallichii
Synonyms Polygonum pensylvanicum, P. mississippiensis, P. pensylvanica var. dura, Polygonum omissum, Polygonum pensylvanicum var. durum, Polygonum pensylvanicum var. eglandulosum, Polygonum pensylvanicum var. laevigatum, Polygonum pensylvanicum var. nesophilum, Polygonum pensylvanicum var. rosiflorum
Name authority (Linnaeus) M. Gómez: Anales Inst. Segunda Enseñ. 2: 278. (1896)
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