Vascular Plants of North Carolina
Account for Pennsylvania Smartweed - Persicaria pensylvanica   (L). M. Gomez
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Section 6 » Family Polygonaceae
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Author(L). M. Gomez
DistributionThroughout the state, no doubt in every county.

Newf. to Ont and MT, south to FL, TX, and CA.
AbundanceGenerally common statewide, possibly less numerous in the far eastern counties.
HabitatMoist soil of forest openings, bottomlands, clearings, wet meadows, coastal thickets, roadsides, other disturbed ground. Generally a wetland species, but often in altered habitats.
See also Habitat Account for General Successional Fields and Forblands
PhenologyFlowering and fruiting late May - November.
IdentificationPennsylvania Smartweed can be told from our other smartweeds by its rather broad and blunt flower spikes, rosy to pink flowers, and glandular-hairy (tack-shaped hairs) on inflorescence stalks. It is freely branched, about 3-6 feet tall, with standard smartweed leaves -- rather long and slender, lanceolate to elliptic, and mostly smooth. This is the familiar smartweed with rather broad and pink spikes, densely flowered, and usually straight (and not curved). Without the flowering spikes, it might be difficult to identify, as would so many others in the genus.
Taxonomic CommentsFormerly named as Polygonum pensylvanicum.

Many species formerly treated in the genus Polygonum have been moved to Persicaria, the smartweeds. These are generally erect and tall plants with terminal and axillary floral spikes; most occur in wetlands. Others remain in Polygonum, the knotweeds, which are generally prostrate to ascending and with inconspicuous axillary flowers. They occur mostly in dry soils and tend to be weedy.

Attention must be paid to the small collars at the junction of the main stem and leaf stems (called ocreae) and whether they possess terminal hairs or bristles. Some keys also refer to the even smaller collars from which flowers emerge (called ocreolae). Another important ID character is the surface of the greenish sepals -- whether smooth or dotted with indentations (punctate).
Other Common Name(s)Pinkweed
State RankS5
Global RankG5
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