Prostrate knotweed Polygonum aviculare L.
Family: Polygonaceae (Smartweed family)
Life cycle: Annual
Habitat: Turf, landscapes, compacted soils
Native status: Introduced from Europe
General description: Prostrate to ascending growth habit with stems up to 2 ft long. Stems are wiry, branched, and swollen at nodes. Leaves alternate, lanceolate to elliptic, pointed at tip, usually less than ¾” long. Ochrea surrounds stem at leaf nodes. Flowers inconspicuous in axillary clusters.
Key ID traits: Prostrate growth, alternate, elliptic leaves with ochrea. Presence in areas with compacted soil.
Similar species: Prostrate spurge has similar growth habit, but has opposite leaves and milky sap.
Miscellaneous: Normally found in areas with highly compacted soils, such as gravel driveways and adjacent to sidewalks. One of the first summer annuals to emerge.