Polygonum ramosissimum subsp. prolificum
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Family: Polygonaceae · Type: Herb · Not Native
Polygonum ramosissimum subsp. prolificum is a non-native California herb in the Polygonaceae family.
Proliferating knotweed is a naturalized annual found in northern Sierra Nevada (Lake Tahoe area) and San Francisco Bay bioregions in wet, saline places at elevations of 100 to 2,000 meters. Flowering from June to October, this plant produces white to pink flowers in small clusters with 2 to 4 crowded blooms. Growing with erect blue-green stems 10 to 80 centimeters tall, it develops stems that darken to dark brown or black when dry. Its leaves are distinctive, with oblanceolate blades 8 to 30 millimeters long, 4 to 6 millimeters wide, having rounded or obtuse tips that are notably longer than the flowering branches. The fruit is small, measuring 1.6 to 2 millimeters long, with a shiny or dull surface that can be smooth or slightly rough.
Habitat and range
Habitat: Wet, saline places
Elevation: 100-2000 m
Outside California: native to eastern North America
Bloom period
Polygonum ramosissimum subsp. prolificum blooms Jun-Oct.
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. prolificum native to California?
No. Polygonum ramosissimum subsp. prolificum is not native to California (recorded as not native).
When does Polygonum ramosissimum subsp. prolificum bloom?
Polygonum ramosissimum subsp. prolificum blooms Jun-Oct.
What plant family does Polygonum ramosissimum subsp. prolificum belong to?
Polygonum ramosissimum subsp. prolificum is in the Polygonaceae family, genus Polygonum.
What habitat does Polygonum ramosissimum subsp. prolificum grow in?
Polygonum ramosissimum subsp. prolificum grows in Wet, saline places.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · CalPhotos
Last updated 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.