Polygonum marinense

Marin knotweed

Family: Polygonaceae · Type: annual · Native

Conservation status: CNPS 3.1

Marin knotweed is a California native annual found in northern coastal counties including Marin, Napa, Solano, and Sonoma in coastal salt and brackish marshes at elevations below 10 meters. Flowering from April to August, this plant produces white to pink flowers in small clusters, with each flower approximately 3 to 3.5 millimeters long. Growing with prostrate to ascending succulent stems 15 to 40 centimeters long that range from green to red-tinged, it has distinctive ribbed branches emerging from the base. Its leaves are elliptic to obovate, generally 20 to 35 millimeters long with a rounded tip, often displaying a reddish tinge along the margins. The fruit is small, shiny brown, and ovate, measuring 2.8 to 3.4 millimeters long and developing late in the season.

Habitat: Coastal salt, brackish marshes, swamps

Bloom period: Apr-Aug

Elevation: < 10 m

Bioregions: n CCo (&lt 15 sites, Marin, Napa, Solano, Sonoma cos.).

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