Callitriche palustris
Vernal water-starwort
(c) Steve Matson, some rights reserved (CC BY) · licence
Family: Plantaginaceae · Type: Herb · Native
Callitriche palustris (Vernal water-starwort) is a native California herb in the Plantaginaceae family, recognized by high elevation range and leaf shape are key features.
Vernal water-starwort is a California native perennial found in the California Floristic Province and Great Basin in submerged habitats, with populations occurring at elevations up to 4,000 meters. Flowering from May to August, this aquatic plant produces tiny, inconspicuous flowers in delicate rosettes that float on water surfaces or become stranded at lake and stream edges. Growing with thin, adaptable stems, it forms distinctive floating and submersed leaf structures that change shape depending on its aquatic environment. Its leaves are uniquely variable, with submersed leaves appearing linear-oblong and floating leaves developing a spoon-shaped form that gradually narrows to a short petiole, typically 3 to 4.5 millimeters long. In terrestrial or emergent conditions, the plant produces compact leaves about 1 millimeter wide, demonstrating remarkable morphological flexibility across different water habitats.
Identification and appearance
Key characters: Co-occurs with 7 species; high elevation range and leaf shape are key features
Habitat and range
Habitat: Submerged, with floating rosettes or becoming stranded at edge of lake, pools, or streams
Elevation: < 4000 m
California counties: Shasta, Fresno, Modoc, Sonoma, Butte, Siskiyou, Lassen, San Bernardino, Mendocino, San Diego, Humboldt, Mono, Santa Cruz, Sierra, Placer, El Dorado, Alpine, Santa Barbara, Inyo, Tuolumne
Outside California: northern and western United States, Canada, Europe, Asia, naturalized in Australia
Bloom period
Callitriche palustris blooms May-Aug.
How to tell it apart
vs Nasturtium: Nasturtium has bright yellow or white 4-petaled flowers; Callitriche has no petals, just tiny styles.; vs Lemna: Lemna is free-floating duckweed with no roots in substrate; Callitriche is rooted with opposite-leaved stems.; vs Ludwigia: Ludwigia has showy yellow flowers and consistent leaf shape; Callitriche lacks petals and has dimorphic leaves.; vs Soleirolia: Soleirolia is terrestrial with round leaves; Callitriche is aquatic with narrow or spoon-shaped leaves.; vs Stellaria: Stellaria has notched white petals on terrestrial plants; Callitriche lacks petals and forms aquatic rosettes.
Frequently asked questions
Is Callitriche palustris native to California?
Yes. Callitriche palustris is native to California (recorded as native).
When does Callitriche palustris bloom?
Callitriche palustris blooms May-Aug.
Where in California does Callitriche palustris grow?
Callitriche palustris occurs in Shasta, Fresno, Modoc, Sonoma, Butte, Siskiyou, Lassen, San Bernardino and other counties, at elevations of < 4000 m.
What plant family does Callitriche palustris belong to?
Callitriche palustris is in the Plantaginaceae family, genus Callitriche.
What habitat does Callitriche palustris grow in?
Callitriche palustris grows in Submerged, with floating rosettes or becoming stranded at edge of lake, pools, or streams.
Related species
Other California species in the same genus, family, or bioregion.
- Callitriche sp. — Water-starwort
- Callitriche stagnalis — Pond water starwort
- Callitriche trochlearis — Effluent water starwort
- Callitriche fassettii — Fassett's water starwort
- Callitriche heterophylla — Varied leaved water starwort
- Callitriche heterophylla var. bolanderi — Bolander's water starwort
- Collinsia antonina — San antonio collinsia
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.