Persicaria posumbu (Buch.-Ham. ex D. Don) H. Gross

Locations ofPersicaria posumbu (Buch.-Ham. ex D. Don) H. Gross in Virginia

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Botanical Name
Persicaria posumbu (Buch.-Ham. ex D. Don) H. Gross
Common Name
Oriental Lady's-thumb
Flora of Virginia Name/Status
Not in Flora of Virginia (discovered after its publication).
Native of e. Asia, Persicaria posumbu was only recently reported from North America, growing in the Delaware River floodplain in both New York and New Jersey; see Atha, D. and S. Rall. 2020. First report of Persicaria posumbu (Polygonaceae) for North America. Phytoneuron 2020-86: 1–7. In September 2022, a very large population of the species was discovered in Augusta County, Virginia by Drew Chaney; three weeks later, he discovered a smaller population in Madison County. These sudden discoveries suggested that P. posumbu is likely occurring undetected at additional Virginia stations. This species is similar to Persicaria longiseta, differing in several subtle characters. A recent search of GMUF specimens filed under P. longiseta by Rod Simmons yielded five specimens of P. posumbu from four counties dating back to 1968, and recent collecting has added four more counties. Evidently this species has been present in the flora but unrecognized for decades. Searches of other herbaria are likely to turn up additional records.

This species can be distinguished from Persicaria longiseta by the following characters: branching from near the base; leaf blades cuneate at base and caudate at the tip; leaf surfaces strigose, often with a lunate, purple blotch; inflorescences lax with remote fascicles; tepals pale pink to white.
Roadsides, weedy clearings, disturbed forests and floodplains. Currently known from ten counties but likely more widespread.
Native Status

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