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Polygonum Pensylvanicumor

Polygonum Pensylvanicumor

Polygonum Pensylvanicum

Pennsylvania smartweed is a member of the Polygonaceae (Smartweed) family. The smartweed family includes about 900 species that range from annual herbs to perennial trees. The family includes buckwheat, dock, and rhubarb. The genus Polygonum typically has simple leaves which often have dark blotches on them. Flowers do not have petals but have sepals that mimic petals. In some manuals, Pennsylvania smartweed is called Persicaria pensylvanica (L.) M. Gómez.

Polygonum

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).

[Persicaria mississippiensis (Stanford) Small, morePersicaria pensylvanica var. dura (Stanford) C.F. Reed, Polygonum longistylum var. omissum (Greene) Stanford, Polygonum mexicanum auct. non Small, Polygonum mississippiense Stanford, Polygonum mississippiense var. interius Stanford, Polygonum pennsylvanicum L., Polygonum pensylvanicum L., Polygonum pensylvanicum var. durum Stanford, Polygonum pensylvanicum var. eglandulosum J.C. Myers, Polygonum pensylvanicum var. genuinum Fern., Polygonum pensylvanicum var. laevigatum Fern., Polygonum pensylvanicum var. pensylvanicum , Polygonum pensylvanicum var. rosiflorum J.B.S. Norton.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/ 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. Flowering May-Dec. Moist, disturbed places, ditches, riverbanks, cultivated fields, shorelines of ponds and reservoirs; 0-1800 m; N.B., Nfld. and Labr. (Nfld.), N.S., Ont., Que.; Ala., Alaska, Ariz., Ark., Calif., Colo., Conn., Del., D.C., Fla., Ga., Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Pa., R.I., S.C., S.Dak., Tenn., Tex., Utah, Vt., Va., W.Va., Wis., Wyo.; South America (Ecuador); Europe (England, Spain). 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). (Source: swbiodiversity.org)

 

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