Polygonum spergulariiforme
Spurry knotweed
(c) Shaan Aroeste, some rights reserved (CC BY) · licence
Family: Polygonaceae · Type: Annual · Native
Polygonum spergulariiforme (Spurry knotweed) is a native California annual in the Polygonaceae family, recognized by very narrow linear leaves and large open flowers.
Spurry knotweed is a California native annual found in northwestern California, the Cascade Range, northern Sierra Nevada, San Francisco Bay Area, and western Modoc Plateau in open, rocky places including serpentine habitats at elevations of 10 to 2,000 meters. Flowering from June to October, this plant produces delicate pink or white flowers in dense, spike-like clusters with 2 to 5 crowded blooms. Growing 5 to 50 centimeters tall with widely spreading green branches, it has a distinctively papillate-scabrous stem that becomes smoother with age. Its linear to lanceolate leaves are narrow, measuring 35 to 60 millimeters long and 1 to 3 millimeters wide, with flat or slightly rolled margins and acute, mucronate tips. The fruit is a shiny black, narrow elliptic seed 3 to 5 millimeters long with smooth to slightly striated surfaces.
Identification and appearance
Key characters: 29 sympatric species; key features are very narrow linear leaves and large open flowers
Habitat and range
Habitat: Open, rocky places (including serpentine)
Elevation: 10-2000 m
California counties: Nevada, Trinity, Lassen, Modoc, Humboldt, Lake, Siskiyou, Del Norte, Marin, Butte, Plumas, Shasta, El Dorado, Mendocino, Napa, Tuolumne, Sierra, Tehama, Mono
Outside California: to British Columbia
Bloom period
Polygonum spergulariiforme 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 spergulariiforme native to California?
Yes. Polygonum spergulariiforme is native to California (recorded as native).
When does Polygonum spergulariiforme bloom?
Polygonum spergulariiforme blooms Jun-Oct.
Where in California does Polygonum spergulariiforme grow?
Polygonum spergulariiforme occurs in Nevada, Trinity, Lassen, Modoc, Humboldt, Lake, Siskiyou, Del Norte and other counties, at elevations of 10-2000 m.
What plant family does Polygonum spergulariiforme belong to?
Polygonum spergulariiforme is in the Polygonaceae family, genus Polygonum.
What habitat does Polygonum spergulariiforme grow in?
Polygonum spergulariiforme grows in Open, rocky places (including serpentine).
Related species
Other California species in the same genus, family, or bioregion.
- Polygonum argyrocoleon — Persian knotweed
- Polygonum austiniae — Mrs. austin's knotweed
- Polygonum aviculare — Knotweed
- Polygonum aviculare subsp. aviculare
- Polygonum aviculare subsp. buxiforme
- Polygonum aviculare subsp. depressum
- Pterostegia drymarioides — Fairy mist
- Pterostegia sp. — Woodland threadstem
- Rumex acetosella — Sheep sorrel
- Rumex britannica — Pale dock
Sources: Jepson eFlora · Index of California Plant Names · 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.