Polygonum parryi

Parry's or prickly knotweed

Family: Polygonaceae · Type: annual · Native

Parry's knotweed is a California native annual found in northwestern California, the Cascade Range, Sierra Nevada, San Francisco Bay Area, and Peninsular Ranges in vernally moist, open, sandy, rocky places at elevations of 500 to 2,000 meters. Flowering from May to July, this plant produces tiny flowers with red perianth and white margins, clustered closely in most leaf axils. Growing as a compact, cushion-like plant with erect green-brown stems just 2 to 5 centimeters tall, it forms a dense, low-growing cluster. Its leaves are remarkably narrow, lance-linear or awl-shaped, measuring 5 to 13 millimeters long and less than a millimeter wide, with spine-tipped edges and margins rolled underneath. The small dark-brown, shiny fruits are slightly protruding and approximately 1.2 to 1.6 millimeters long.

Habitat: Vernally moist, open, sandy, rocky places

Bloom period: May-Jul

Elevation: 500-2000 m

Bioregions: NW, CaR, SN, SnFrB, PR

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