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Smartweed - Polygonum hydropiperoides
Family: Polygonaceae

THIS PAGE IS UNDER CONSTRUCTION.

Description

The leaves of Polygonum are alternate with tubelike sheathing stipules (ocrea) and stems with swollen nodes. The flowers have no petals, but the sepals resemble petals. The fruit is an achene.

Polygonum arifolium is an annual with slender stems that are weak and up to 2 m or more long, erect at first, later reclining or intertwined with other vegetation. The stem is ribbed-angled and retrorsely barbed. Leaves are petioled and pubescent. Leaf blades are about 15 cm long and 7 broad, oblong or ovate-oblong above, with horizontally divergent (hastate) basal lobes. Flowers are few, pink to purplish to white, in short racemes on slender barbed stalks. The achene is lenticular.

Polygonum hydropiperoides is a perennial. The lower portion of stems are decumbent and root at the nodes. Flowering stems are erect, mostly about 5 dm tall. Leaves are short-stalked to sessile, the blades lanceolate to nearly linear-lanceolate, pubescent, about 1 cm wide and 7 to 10 cm long. The flowers are roseate at the base of the inflorescence; the upper most flowers, pink or cream-white, rarely greenish, purplish, or white. The sepals lack glandular dots. The achene is 3-angled.

Interesting facts

Both halberd-leaved tearthumb and smartweed grow in wet meadows, marshes, shorelines of lakes and ponds, and open areas in wet woodlands. Polygonum hydropiperoides is often found in extensive colonies along shorelines and in exposed bottoms of ponds or lakes during times of low water. It may also grow in drainage and irrigation ditches and canals. The seeds are dispersed by animals or by water.

Dense colonies of P. hydropiperoides can impede water flow in irrigation ditches (Tarver et al. 1986) and restrict recreational activities along shoreline areas. The seeds of smartweed are eaten by birds, waterfowl and several small mammals Tarver et al. 1986).

Links to more information

• US Army Corp Noxious Plant Database

Website, video, and graphics by Rob Nelson
For more information on this plant or management please contact US Army Corp of Engineers

Smartweed Video

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