Polygonum ramosissimum subsp. ramosissimum
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Family: Polygonaceae · Type: Annual · Native
Polygonum ramosissimum subsp. ramosissimum is a native California annual in the Polygonaceae family, recognized by yellow-green color, tall stature, and saline marsh habitat.
Knotweed is a California native annual found in northern California Coast Ranges, San Francisco Bay Area in disturbed places and saline marshes at elevations below 200 meters. Flowering from July to September, this plant produces white to yellow or pink flowers clustered in spike-like inflorescences with small flowers 2 to 5 millimeters long. Growing with yellow-green stems reaching 30 to 200 centimeters tall, it develops branching stems with distinctive height variations between main and branch stems. Its leaves are narrowly elliptic to lanceolate, measuring 35 to 70 millimeters long with blade widths of 7 to 18 millimeters, featuring acute to acuminate tips. The fruit is small, shiny or dull, and measures 2.5 to 3.5 millimeters in length.
Identification and appearance
Key characters: 28 sympatric species; key features are yellow-green color, tall stature, and saline marsh habitat
Habitat and range
Habitat: Disturbed places, saline marshes
Elevation: < 200 m
Outside California: North America
Bloom period
Polygonum ramosissimum subsp. ramosissimum blooms Jul-Sep.
How to tell it apart
vs Euphorbia: Polygonum has swollen stem joints with papery sheaths; Euphorbia has milky sap when broken.; vs Persicaria: Hold node sheaths to light—Polygonum's are translucent and split; Persicaria's are opaque and intact.; vs Eriogonum: Polygonum has papery sheaths at nodes; Eriogonum has flowers in cup-like involucres.; vs Acmispon: Polygonum has swollen stem nodes; Acmispon has compound leaves with 3-5 leaflets.; vs Atriplex: Polygonum has papery stem sheaths; Atriplex has mealy or scurfy coating on leaves.
Frequently asked questions
Is Polygonum ramosissimum subsp. ramosissimum native to California?
Yes. Polygonum ramosissimum subsp. ramosissimum is native to California (recorded as native).
When does Polygonum ramosissimum subsp. ramosissimum bloom?
Polygonum ramosissimum subsp. ramosissimum blooms Jul-Sep.
What plant family does Polygonum ramosissimum subsp. ramosissimum belong to?
Polygonum ramosissimum subsp. ramosissimum is in the Polygonaceae family, genus Polygonum.
What habitat does Polygonum ramosissimum subsp. ramosissimum grow in?
Polygonum ramosissimum subsp. ramosissimum grows in Disturbed places, saline marshes.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · CalPhotos
Last updated 2026-10-06
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.