Callitriche fassettii
Fassett's water starwort
(c) Adam J. Searcy, some rights reserved (CC BY) · licence
Family: Plantaginaceae · Type: Herb · Native
Callitriche fassettii (Fassett's water starwort) is a native California herb in the Plantaginaceae family, recognized by lack of floating rosettes and short fruit peduncles.
Fassett's water starwort is a California native perennial found in northern California regions including the Central Valley, Sierra Nevada foothills, San Francisco Bay Area, and Modoc Plateau in submerged habitats like streams and ponds at elevations below 2,100 meters. Flowering from April to July, this aquatic plant produces tiny, inconspicuous flowers in delicate axillary clusters. Growing as scattered or dense underwater stands, it forms slender stems with submersed linear leaves that taper from the base. Its leaves are narrow and elongated, adapted to underwater environments with flexible, thread-like structures. The fruit is broadly winged, small and compact, measuring approximately 1.5 to 1.8 millimeters wide.
Identification and appearance
Key characters: Co-occurs with 7 species; lack of floating rosettes and short fruit peduncles are diagnostic
Habitat and range
Habitat: Submerged in streams, ponds
Elevation: < 2100 m
Outside California: Oregon, Ontario, Nebraska
Bloom period
Callitriche fassettii blooms Apr-Jul.
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 fassettii native to California?
Yes. Callitriche fassettii is native to California (recorded as native).
When does Callitriche fassettii bloom?
Callitriche fassettii blooms Apr-Jul.
What plant family does Callitriche fassettii belong to?
Callitriche fassettii is in the Plantaginaceae family, genus Callitriche.
What habitat does Callitriche fassettii grow in?
Callitriche fassettii grows in Submerged in streams, ponds.
Related species
Other California species in the same genus, family, or bioregion.
- Callitriche heterophylla — Varied leaved water starwort
- Callitriche heterophylla var. bolanderi — Bolander's water starwort
- Callitriche heterophylla var. heterophylla — Varied leaved water starwort
- Callitriche longipedunculata — Longstock water-starwort
- Callitriche marginata — California water starwort
- Callitriche palustris — Vernal water-starwort
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.