Polygonum aviculare subsp. buxiforme

Family: Polygonaceae · Type: annual · Not Native

Knotweed is a naturalized annual found in California in disturbed places, nondrifting sands, borders of marshes, and dunes at elevations below 3,000 meters. Flowering from July to November, this plant produces small green flowers with white margins in tight clusters. Growing with prostrate to ascending stems that form dense mats 20 to 70 centimeters long, it has multiple branching stems that spread across the ground. Its leaves are lanceolate to elliptic, 6 to 30 millimeters long, with distinctive silvery ocreae (stipule-like sheaths) that persist especially on upper stems. The plant produces light-brown to brown fruits that are 2 to 2.8 millimeters long, typically hidden within the flower clusters.

Habitat: Disturbed places, nondrifting sands, borders of marshes, dunes

Bloom period: Jul-Nov

Elevation: < 3000 m

Bioregions: CA

Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Jepson eFlora, Cal-IPC, and more.