Prostrate Knotweed, Common Knotgrass, Wireweed
Plantae > Tracheophyta > Magnoliopsida > Caryophyllales > Polygonaceae > Polygonum > Polygonum aviculare · Polygonaceae (Buckwheat / Knotweed family) · Simple, deciduous annual herb
Species
Polygonum aviculare
Leaf Type
Simple, deciduous annual herb
Family
Polygonaceae (Buckwheat / Knotweed family)
Shape
Lanceolate to narrow-elliptic or oblanceolate
Size
Individual leaves are small, typically 0.5 to 1.5 cm long and 2 to 5 mm wide
Margin
Entire (smooth, untoothed edges)
Arrangement
Alternate along wiry, prostrate stems with silvery sheath-like ocreae at nodes
Rarity
Very Common (extremely frequent weed in lawn and urban environments)
Color & Pattern
Dull green to bluish-green foliage with distinct reddish-pink to purplish wiry stems
Venation Pattern
Pinnate with a single visible central midrib, secondary veins faint
Texture & Surface
Smooth, slightly leathery to papery texture; upper and lower surfaces are mostly glabrous
Description
Prostrate Knotweed is a tough, low-growing annual weed forming dense, mat-like ground cover. It features wiry, jointed stems that branch extensively horizontally. Tiny green to pinkish flowers nestle in the leaf axils. It thrives in high-traffic areas where other plants fail due to soil compaction.
Key Features
Prostrate growth habit, reddish-pink wiry stems with jointed nodes, silvery papery sheaths (ocreae) wrapping stem joints, small lanceolate leaves.
Habitat
Disturbed soils, compacted turf, sidewalk cracks, roadsides, agricultural fields, and heavily foot-trafficked lawns
Geographic Range
Cosmopolitan distribution; native to Eurasia but naturalized across North America, South America, Australia, and parts of Africa
Condition Notes
Fair to Good condition; showing typical wear from ground growth among turfgrass with slight yellowing on older lower leaves.
Interesting Facts
The seeds of knotgrass are a vital food source for many wild ground-foraging birds. Its ability to tolerate severe soil compaction allows it to survive in places like footpaths and driveway edges.
Medicinal & Uses
Historically used in traditional herbal medicine as an astringent and diuretic. Seeds and young leaves were occasionally consumed, though rarely cultivated deliberately today.
Ecological Role
Colonizes eroded or compacted soil, preventing further soil erosion. Serves as a host plant and food source for various insects and small granivorous birds.
Similar Species
Spotted Spurge (Euphorbia maculata) - distinguished by milky white sap when broken and opposite leaves; Common Purslane (Portulaca oleracea) - has much thicker succulent leaves.
Foraging Tips
Look in heavily trampled soil or turf edges. Ensure harvesting occurs away from areas sprayed with lawn herbicides or road runoff.
Toxicity Warning
Non-toxic to mildly toxic if consumed in large quantities due to oxalic acids and potential concentration of nitrates from treated soils.
Notes
Yard