Tearthumb

Polygonum arifolium

Weed Description
A branched annual with arrow-shaped leaves and stems with many prickles that are turned backward. Tearthumb primarily occurs as an aquatic weeds of shorelines, marshes, and swamps.

Leaves
Leaves are arrow-shaped, but with the basal lobes pointing outward (hastate). Leaves are hairy, approximately 4 to 4 1/2 inches long, and occur on petioles that range from 1 1/4 to 4 1/2 inches in length.

Stems
Branching, with many prickles turned oppositely (retrorsely barbed) from the direction of the stem.

Flowers
Occur in terminal spikes at the ends of branches with each spike containing 2 to 4 flowers. Flowers are white to pink in color and occur on the ends of leafless flower stalks (peduncles).

Fruit
A reddish brown, globular nutlet.

Identifying Characteristics
The arrow-shaped leaves with bases that point outward and prickly stems help to distinguish tearthumb from most other aquatic shoreline weeds. However, Arrow-leaved Tearthumb (Polygonum sagittatum) is very similar in appearance and growth habit but has much smaller, hairless leaves with lobes that encircle the stem unlike those of tearthumb.

Office of Programs

University of Missouri

Tearthumb

Polygonum arifolium