Persicaria hydropiper
Waterpepper, Waterpepper
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Family: Polygonaceae · Type: Herb · Not Native
Persicaria hydropiper (Waterpepper) is a non-native California herb in the Polygonaceae family, recognized by found only in specific foothill counties.
Waterpepper is a naturalized annual found in northern and central California Floristic Province in shores of lakes, ponds, riverbanks, forested wetlands, pastures, and disturbed ground at elevations below 1,500 meters. Flowering from May to December, this plant produces green-white or pink flowers in small clusters with reddish margins. Growing 20 to 60 centimeters tall with ascending to erect stems that are gland-dotted, it forms dense patches with lanceolate leaves. Its leaves have distinctive ocrea (sheaths) 8 to 15 millimeters long, brown and cylindric, with truncate margins and short bristles. The fruit is small, lens-shaped, and brown-black, measuring 2 to 3 millimeters long.
Identification and appearance
Key characters: Geographically isolated; found only in specific foothill counties
Habitat and range
Habitat: Shores of lakes, ponds, riverbanks, forested wetlands, pastures, disturbed ground
Elevation: < 1500 m
California counties: Sonoma, Amador, Calaveras, Lake, Marin, Placer, Sacramento, Sutter, Trinity, Tuolumne, Butte, El Dorado, Humboldt, Inyo, Mendocino, Nevada, Plumas, Shasta, Siskiyou, Glenn, Tehama, Solano, San Joaquin, Yuba, Los Angeles, Stanislaus, Santa Clara, Yolo
Outside California: to northern and eastern North America, also Asia, Africa, Australia, native to Europe
Bloom period
Persicaria hydropiper blooms May-Dec.
How to tell it apart
vs Polygonum: Persicaria has opaque stem sheaths; Polygonum has translucent sheaths that split into two lobes.; vs Rumex: Persicaria has spike-like pink/white flower clusters; Rumex has branched greenish flower clusters.; vs Trifolium: Persicaria has spike/head flower clusters and papery stem sheaths; Trifolium has clover heads and no sheaths.; vs Salix: Persicaria is an herb with flower spikes; Salix is a woody shrub with catkins.; vs Phytolacca: Persicaria has small pink/white flowers in spikes; Phytolacca has white-green flowers and dark purple berries.
Frequently asked questions
Is Persicaria hydropiper native to California?
No. Persicaria hydropiper is not native to California (recorded as not native).
When does Persicaria hydropiper bloom?
Persicaria hydropiper blooms May-Dec.
Where in California does Persicaria hydropiper grow?
Persicaria hydropiper occurs in Sonoma, Amador, Calaveras, Lake, Marin, Placer, Sacramento, Sutter and other counties, at elevations of < 1500 m.
What plant family does Persicaria hydropiper belong to?
Persicaria hydropiper is in the Polygonaceae family, genus Persicaria.
What habitat does Persicaria hydropiper grow in?
Persicaria hydropiper grows in Shores of lakes, ponds, riverbanks, forested wetlands, pastures, disturbed ground.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · Index of California Plant Names · 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.