Polygonum argyrocoleon

Persian knotweed

Family: Polygonaceae · Type: perennial · Not Native

Persian knotweed is a naturalized perennial found in southern California, particularly in disturbed places and saline soils at elevations below 1,000 meters. Flowering from June to October, this plant produces green-white flowers with pink margins in small, crowded clusters. Growing with decumbent to erect stems 15 to 100 centimeters tall, it has distinctive ribbed green branches that typically emerge from the base. Its lance-linear leaves are blue-green, 15 to 50 millimeters long and 2 to 8 millimeters wide, with flat margins and acute tips. The plant has distinctive ocreae that disintegrate into curly or straight fibers, giving it a unique textural appearance in disturbed landscapes.

Habitat: Disturbed places, often in saline soils

Bloom period: Jun-Oct

Elevation: < 1000 m

Bioregions: CA (esp s)

California counties: Los Angeles, Ventura, San Bernardino, Imperial, Orange, Riverside, San Diego, Kings, Merced, Inyo, Lake, Santa Clara, Fresno, San Luis Obispo, Kern, Siskiyou, Solano, El Dorado, Santa Barbara, San Francisco, Yolo, Marin, Monterey, San Mateo, Lassen, Tulare, Contra Costa, Sierra, Stanislaus

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