Polygonum arifolium (Halberd-leaved Tearthumb)

Polygonum arifolium

Polygonum arifolium L.

Persicaria arifolia (L.) Harolds.

Polygonum arifolium L. var. lentiforme Fernald & Grisc.

Polygonum arifolium L. var. pubescens (Keller) Fernald

Tracaulon arifolium (L.) Raf.

Halberd-leaved Tearthumb

Kingdom	Plantae	Plants, but not fungi, lichens, or algae
Subkingdom	Tracheobionta	Vascular plants—plants with a “circulatory system” for delivering water and nutrients
Division	Magnoliophyta	Flowering plants, also known as angiosperms
Class	Magnoliopsida	Dicotyledons—plants with two initial seed leaves
Subclass	Caryophyllidae	Cacti, many other succulents, carnivorous plants, and leadworts
Order	Caryophyllales	Includes cacti, carnations, amaranths, ice plants, and many carnivorous plants
Family	Polygonaceae	Knotweed or smartweed family
Genus	Polygonum	Greek poly, “many,” and gonu, “knee,” for the swollen jointed stems
Species	arifolium

About plant names...

Halberd-leaved tearthumb is a rather strange-sounding name. “Halberd-leaved,” for its leaves’ resemblance to a rather nasty ancient weapon; “tearthumb,” for the backward-pointing barbs on its stems. The plant is native to eastern North America.

Identification: This vinelike plant has weak stems that are green, pink or red, with many tiny backward-pointing barbs used to support it as it grows over other plants. Plants may be 24-48" (60-121 cm) long. Leaves are shaped like arrowheads, except that the backward-pointing barbs point outward (technically, “hastate”). Leaves are hairy, 4-4½" (10-11 cm) long. Flowerheads are less than ⅜" (1 cm) in diameter, white to light 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. Seeds are rounded reddish-brown nutlets about ⅛" (3.2 mm) around.

8/30/2007 · By User:SB_Johnny

Halberd-leaved tearthumb and its namesake, a halberd from 14th-16th century Sweden.

These similar species are most easily distinguished by leaf shape:

	You are here Polygonum arifolium	*Polygonum sagittatum*
Common Name	Halberd-leaved Tearthumb	Arrow Tearthumb
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.
Range/ Zones
Habitats	Marshes, swamps, wet meadows	Wet, marshy ground
Type	Wild	Wild

Online References:

Polygonum arifolium on the Virginia Tech Weed Identification Guide

Polygonum arifolium on the Connecticut Botanical Society's Connecticut wildflowers site

Polygonum arifolium at the University of Wisconsin's Robert W. Freckmann Herbarium

Polygonum arifolium at the Lady Bird Johnson Wildflower Center

Polygonum arifolium description by Thomas H. Kent, last updated 12 Oct 2018.

Range:

About this map...