Pistia stratiotes
Water lettuce
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Family: Araceae · Type: Herb · Not Native
Pistia stratiotes (Water lettuce) is a non-native California herb in the Araceae family, recognized by Tropical species occasionally appearing as waif - only free-floating aroid in California flora.
Water lettuce is a naturalized aquatic perennial found in the southern Colorado Desert near the Salton Sea in ditches at elevations below 50 meters. Flowering from May to October, this plant produces white flowers nestled within velvety, widely wedge-shaped leaves that are less than 20 centimeters long. Growing as a floating plant that spreads via stolons, it forms dense mats with many plume-like roots and a short, corm-like stem. Its distinctive leaves are soft and hairy, featuring a truncate or notched tip and lengthwise grooves that give the plant a unique, lettuce-like appearance. The plant reproduces through numerous seeds produced in green fruits, creating expansive floating colonies in shallow water environments.
Identification and appearance
Key characters: Tropical species occasionally appearing as waif - only free-floating aroid in California flora
Habitat and range
Habitat: Ditches
Elevation: < 50 m
Outside California: to southeastern United States, tropics worldwide
Bloom period
Pistia stratiotes blooms May-Oct.
How to tell it apart
vs Ludwigia: Pistia floats as rosettes; Ludwigia grows rooted with stems rising above water.; vs Pontederia: Pistia has velvety wedge-shaped leaves in rosettes; Pontederia has glossy heart-shaped leaves on stems.; vs Zantedeschia: Pistia is a tiny floating rosette; Zantedeschia is a large terrestrial plant near gardens.; vs Arum: Pistia is a tiny floating rosette; Arum is a terrestrial plant with arrow-shaped leaves.; vs Lysichiton: Pistia is a tiny floating rosette in warm water; Lysichiton is huge with yellow hood in cold marshes.
Frequently asked questions
Is Pistia stratiotes native to California?
No. Pistia stratiotes is not native to California (recorded as not native).
When does Pistia stratiotes bloom?
Pistia stratiotes blooms May-Oct.
What plant family does Pistia stratiotes belong to?
Pistia stratiotes is in the Araceae family, genus Pistia.
What habitat does Pistia stratiotes grow in?
Pistia stratiotes grows in Ditches.
Related species
Other California species in the same genus, family, or bioregion.
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.