Polygonum sagittatum L.
Persicaria sagittata (L.) Gross.
Polygonum sagittatum L. var. gracilentum Fernald
Tracaulon sagittatum (L.) Small
Tracaulon sagittatum (L.) Small var. gracilentum (Fernald) C.F. Reed
Truellum sagittatum (L.) Soják
These North American natives favor wet, marshy ground.
Identification: These plants have hollow vinelike stems up to 3-6' (91-182 cm) long, with squared edges and tiny, backward-pointing prickles. The prickles help the plant attach to surrounding plants as it meanders over them. Stems may be green, pink, or red. The leaves are shaped like arrowheads, attached via short ⅜" (1 cm) stems. The base of each leaf tends to wrap around the stem. Leaf edges also have tiny prickles. Flowerheads are less than ⅜" (1 cm) in diameter, white to pink in color. Each rounded flowerhead consists of 5-20 individual flowers at the end of a long stem, which emerges from a leaf node. Fruits are small nutlets, brown to black.
These similar species are most easily distinguished by leaf shape:
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|Flowers||Flowerheads are less than ⅜" (1 cm) in diameter, white to light pink, with 5-20 individual flowers at the end of a long stem||Flowerheads are less than ⅜" (1 cm) in diameter, white to pink in color. Each rounded flowerhead consists of 5-20 individual flowers at the end of a long stem.|
|Leaves||Leaves are shaped like arrowheads, except that the backward-pointing barbs point outward (technically, “hastate”). Leaves are hairy, 4-4½" (10-11 cm) long||Shaped like narrow arrowheads, attached via short ⅜" (1 cm) stems. The base of each leaf tends to wrap around the stem. Leaf edges also have tiny prickles.|
|Stem||Vine has weak stems that are green, pink or red, with many tiny backward-pointing barbs, 24-48" (60-121 cm) long||Stems 3-6' (91-182 cm) long, green, pink, or red, hollow, vinelike, with squared edges and tiny, backward-pointing prickles.|
|Fruit||Seeds are rounded reddish-brown nutlets about ⅛" (3.2 mm) around||Small nutlets, brown to black.|
|Habitats||Marshes, swamps, wet meadows||Wet, marshy ground|
Polygonum sagittatum on the Connecticut Botanical Society's Connecticut wildflowers site
Polygonum sagittatum at the University of Wisconsin's Robert W. Freckmann Herbarium
Polygonum sagittatum on the Virginia Tech Weed Identification Guide
Polygonum sagittatum at the Lady Bird Johnson Wildflower Center
Polygonum sagittatum description by Thomas H. Kent, last updated 12 Oct 2018.