Polygonum douglasii

Douglas' knotweed

Family: Polygonaceae · Type: annual · Native

Douglas' knotweed is a California native annual found especially in mountain regions on dry, rocky outcrops, sandy ground, and disturbed places at elevations below 3,500 meters. Flowering from June to October, this plant produces small green to tan flowers with white or pink margins, clustered in spike-like inflorescences. Growing with erect stems 5 to 80 centimeters tall, the plant has angular green stems that are glabrous or sparsely scabrous. Its lance-linear to oblanceolate leaves measure 15 to 55 millimeters long, with margins rolled under and occasionally fine-toothed, and basal leaves that quickly drop off. The fruit is a small, shiny to dull black elliptic seed 3 to 4 millimeters long.

Habitat: Dry, rocky outcrops, sandy ground, disturbed places

Bloom period: Jun-Oct

Elevation: < 3500 m

Bioregions: CA (esp mtns)

California counties: Mono, Siskiyou, Calaveras, Fresno, Tehama, Mariposa, San Bernardino, Plumas, Trinity, Tulare, Alpine, Shasta, Placer, Lassen, San Diego, Modoc, Sierra, Del Norte, El Dorado, Butte, Humboldt, Tuolumne, Nevada, Lake, Inyo, Los Angeles, Amador, Riverside, Yuba, Glenn, Kern, Madera, Mendocino, Sonoma, Merced, Ventura

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