Myriophyllum hippuroides
Western water-milfoil, Western Water-Milfoil
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Family: Haloragaceae · Type: Herb · Native
Myriophyllum hippuroides (Western water-milfoil) is a native California herb in the Haloragaceae family, recognized by leaf arrangement and large bracts.
Western water-milfoil is a California native perennial found in northern Coast Ranges, northern Coast Range Interior, northern Sierra Nevada, San Joaquin Valley, northern Central Coast, and San Francisco Bay Area in ponds and small streams at elevations below 1,100 meters. Flowering from July to September, this aquatic plant produces small, inconspicuous flowers in emergent spikes 3 to 12 centimeters long. Growing to over 1 meter in length with branching underwater stems, it forms dense underwater vegetation. Its leaves are arranged in whorls of 4 to 5 with scattered single leaves, with submerged leaves having fine, linear segments typically 14 to 20 per leaf, each segment less than 10 millimeters long. The plant's delicate, finely divided leaves create intricate underwater structures that provide habitat for aquatic organisms.
Identification and appearance
Key characters: 4 sympatric species; key features are leaf arrangement and large bracts
Habitat and range
Habitat: Ponds, small streams
Elevation: < 1100 m
Outside California: to southern British Columbia, introduced in Oklahoma, Texas
Bloom period
Myriophyllum hippuroides blooms Jul-Sep.
How to tell it apart
vs Hippuris: Myriophyllum has feathery divided leaves; Hippuris has simple, undivided linear leaves in whorls.; vs Elodea: Myriophyllum has leaves pinnately divided into thread-like segments; Elodea has simple oval leaves.; vs Ceratophyllum: Myriophyllum leaves fork from a central spine; Ceratophyllum leaves fork repeatedly without central axis.; vs Ranunculus: Myriophyllum has whorled feathery leaves; aquatic Ranunculus has alternate or basal divided leaves.; vs Potamogeton: Myriophyllum has feathery divided leaves; Potamogeton has simple, entire leaves (blade-like or oval).
Frequently asked questions
Is Myriophyllum hippuroides native to California?
Yes. Myriophyllum hippuroides is native to California (recorded as native).
When does Myriophyllum hippuroides bloom?
Myriophyllum hippuroides blooms Jul-Sep.
What plant family does Myriophyllum hippuroides belong to?
Myriophyllum hippuroides is in the Haloragaceae family, genus Myriophyllum.
What habitat does Myriophyllum hippuroides grow in?
Myriophyllum hippuroides grows in Ponds, small streams.
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.