Virginia Tech Weed Identification Guide

Arrow-leaved Tearthumb: Polygonum sagittatum

Weed Description:  A branched annual with arrow-shaped leaves and stems with many prickles that are turned backward.   Arrow-leaved tearthumb primarily occurs as an aquatic weeds of shorelines, marshes, and swamps.
Leaves:  Without hairs, approximately 1 1/4 to 3 inches long, overall arrow-shaped in appearance.  Leaf bases often encircle the stem and give the leaves even more of an arrowhead appearance.
Stems:  Branching, with many prickles turned oppositely (retrorsely barbed) from the direction of the stem.

Flowers: Occur in small clusters at the ends of branches.   Flowers are white to pink in color and occur on the ends of leafless flower stalks (peduncles).

Fruit:  A brown to black nutlet.

Identifying Characteristics:  The arrow-shaped leaves and prickly stems helps to distinguish arrow-leaved tearthumb from most other aquatic shoreline weeds.  However, Tearthumb (Polygonum arifolium) is very similar in appearance and growth habit but has much larger hairy leaves with lobes that point outward unlike those of arrow-leaved tearthumb.