Callitriche trochlearis
Effluent water starwort
Family: Plantaginaceae · Type: Herb · Native
Callitriche trochlearis (Effluent water starwort) is a native California herb in the Plantaginaceae family, recognized by low elevation coastal range and abrupt wing transition are key features.
Effluent water starwort is a native perennial found in northwestern and central western California in aquatic habitats at elevations up to 500 meters. Flowering from March to June, this delicate plant produces small white flowers in submersed and floating environments. Growing with slender stems, it develops distinctive leaf types with submersed leaves lance-linear and floating leaves spoon-shaped. Its leaves display remarkable adaptability, changing shape depending on whether they are underwater, emerging, or on land. The tiny dark brown to black fruit is approximately 1 to 1.5 millimeters wide, with a shallow groove and a uniformly wide wing that transitions abruptly to the fruit wall.
Identification and appearance
Key characters: Co-occurs with 7 species; low elevation coastal range and abrupt wing transition are key features
Habitat and range
Habitat: Becoming stranded or submersed < +- 6 dm
Elevation: < +- 500 m
Outside California: western Oregon
Bloom period
Callitriche trochlearis blooms Mar-Jun.
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 trochlearis native to California?
Yes. Callitriche trochlearis is native to California (recorded as native).
When does Callitriche trochlearis bloom?
Callitriche trochlearis blooms Mar-Jun.
What plant family does Callitriche trochlearis belong to?
Callitriche trochlearis is in the Plantaginaceae family, genus Callitriche.
What habitat does Callitriche trochlearis grow in?
Callitriche trochlearis grows in Becoming stranded or submersed < +- 6 dm.
Related species
Other California species in the same genus, family, or bioregion.
- Callitriche fassettii — Fassett's water starwort
- 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
- Collinsia antonina — San antonio collinsia
- Collinsia bartsiifolia — White blue eyed mary
- Collinsia bartsiifolia var. bartsiifolia — White blue eyed mary
- Collinsia bartsiifolia var. davidsonii — Davidson's blue eyed mary
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.