Vascular Plants of North Carolina
Account for Arrowleaf Tearthumb - Persicaria sagittata   (L.) H. Gross ex Nakai
Members of Polygonaceae:
Members of Persicaria with account distribution info or public map:
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Section 6 » Family Polygonaceae
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Author(L.) H. Gross ex Nakai
DistributionThroughout the state; no doubt found in every county.

Newf. to Man., south to FL and TX.
AbundanceCommon statewide, except infrequent to locally frequent in the far eastern counties. Surprisingly, no records yet for well-worked Carteret and Hyde counties.
HabitatWet to seasonally wet marshes, beaver pond marshes, impoundment margins, bottomlands and floodplains, montane seepage bogs, roadside ditches, powerlines.
PhenologyFlowering and fruiting May-November.
IdentificationArrowleaf Tearthumb is easy to identify by its sprawling stems (up to 6 feet long) and branches that are beset with sharp, stiff, hooked prickles. Stems usually are dull red color. Leaves are narrowly elliptical or lance-shape, with 2 backward pointing lobes. Halberd-leaf Tearthumb (P. arifolia) has much broader leaves with triangular basal lobes that point sideways. Each has small balls of pink to white flowers on long stalks, generally held above the leaves. When walking through a marsh, be alert to its presence, as stands of it can easily tear your flesh and clothing -- a very painful reminder!
Taxonomic CommentsMany references still name it as Polygonum sagittatum.

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)Arrow-vine
State RankS5
Global RankG5
State Status
US Status
USACE-agcpOBL link
USACE-empOBL link
County Map - click on a county to view source of record.
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B.A. SorrieMarsh by Ray's Mill Creek, just SE of Aberdeen Lake, late May 2015. MoorePhoto_natural
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