Polygonum aviculare subsp. neglectum
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Family: Polygonaceae · Type: Annual · Not Native
Polygonum aviculare subsp. neglectum is a non-native California annual in the Polygonaceae family.
Prostrate knotweed is a naturalized annual found in California in disturbed places at elevations below 1,500 meters. Flowering from June to November, this plant produces small green flowers with pink or red margins, clustered one to three per stem. Growing with multiple prostrate to erect stems 15 to 60 centimeters long that branch from the base, it spreads widely across disturbed ground. Its narrowly elliptic leaves are 12 to 34 millimeters long, about 3 to 6 times longer than wide, with acute or obtuse tips. The dark-brown fruit is three-angled and slightly textured, maturing to 1.2 to 1.8 millimeters long.
Habitat and range
Habitat: Disturbed places
Elevation: < 1500 m
Outside California: North America, Europe
Bloom period
Polygonum aviculare subsp. neglectum blooms Jun-Nov.
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 aviculare subsp. neglectum native to California?
No. Polygonum aviculare subsp. neglectum is not native to California (recorded as not native).
When does Polygonum aviculare subsp. neglectum bloom?
Polygonum aviculare subsp. neglectum blooms Jun-Nov.
What plant family does Polygonum aviculare subsp. neglectum belong to?
Polygonum aviculare subsp. neglectum is in the Polygonaceae family, genus Polygonum.
What habitat does Polygonum aviculare subsp. neglectum grow in?
Polygonum aviculare subsp. neglectum grows in Disturbed places.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · CalPhotos
Last updated 2026-09-30
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.