Polygonum aviculare L.

Family: Polygonaceae

Pertinent Synonyms & Notes (particularly those used in California; go to GRIN for other synonyms)

Polygonum arenastrum Boreau

Pertinent Common Names (particularly those used in California; go to GRIN for other common names)

common knotweed, prostrate knotweed

Primary Disseminule Type

fruit (with or without attached perianth)

Description (diagnostics are in brown)

Disseminule is a fruit with or without attached, partially connate tepals (=perianth).

Perianth 5-lobed, green or reddish-brown with white to red margins, 1.8–5.5 mm long, tube 20–57% of perianth length, midvein branched or unbranched.

Fruit an achene, ovate with 2–3-parted apex, rarely biconvex or typically ± trigonous (one face narrower than the others, faces flat to concave), 1.2–4.2 mm long x 1.2 (narrower face)–1.5–2 mm wide. Surface light to dark purplish-brown, glabrous, dull to semi-glossy, minutely granular (striate-tubercled under magnification). Late-season fruits are larger (2–5 mm long).

Similar Species

Similar Species Comparison Chart

Risk Assessment (codes in yellow or red indicate cause for concern; assessments are current as of mid-2011; click AUQP, NZBORIC, or NZBPI for access to the most recent versions of these databases and possible assessment changes)