prostrate knotweed

Family

Polygonaceae

Scientific Name

Polygonum aviculare

Synonyms (former Scientific Names):

Polygonum aviculare var. vegetum

Polygonum heterophyllum

Polygonum monspeliense

Habit

Emerges in the early spring, but can continue to emerge in the late spring and summer as well. Flowering occurs from June through November.

Leaves

Leaves begin looking almost grass-like and have a waxy whitish coating. Mature leaves are broad leaves that are narrowed at the base, ranging from lanceolate, elliptic to oblong shapes. The petioles are short and have a conspicuous ocrea sheathing the stem at the leaf base.

Identifying Characteristics

The plant forms mats or clusters of dead mesh-like stems that remain throughout the winter.

Flower Seed Head

Flowers appear in 1 to 5 axillary clusters. They are small white to green with some pinkish margins, lacking petals.

Seed Fruit

The friut contains the seed (achene). Achense are about 2 to 3 mm long teardrop-shaped with dark reddish brown to black coloring.

Where Found

Prostrate knotweed can infest turfgrass, nursery crops, landscapes, and areas that is damaged by traffic such as pathways. Grows well in stressed areas.