Vegetative plant. Key characteristics: prostrate knotweed emerges in the late winter/very early spring. Young emerging leaves may be mistaken for a grass plant because of their linear shape. Like other members of the smartweed family, an ocrea (sheath-like structure) is present at the leaf axils.
Prostrate knotweed forms dense mats as it approaches maturity.
Prostrate knotweed thrives on hard, compacted sites, such as in close proximity to sidewalks.
Seed. Seed are ovate and approximately 3.0 mm long.
Appreciation is expressed to Dr. Aaron Hager of the University of Illinois for contributing to this page.
Life cycle: summer annual.