Myriophyllum spicatum
Eurasian water-milfoil, Eurasian Water-Milfoil
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Family: Haloragaceae · Type: Herb · Not Native
Conservation status: Cal-IPC Yes
Myriophyllum spicatum (Eurasian water-milfoil) is a non-native California herb in the Haloragaceae family, recognized by high segment count (≥28) and uniform arrangement are key.
Eurasian water-milfoil is a naturalized aquatic perennial found in diverse regions including the northern Sierra Nevada, Sacramento Valley, San Francisco Bay Area, southern California coast, and Mojave Desert in ditches and lake margins at elevations below 2,080 meters. Flowering from July to September, this invasive plant produces small, understated flowers in emergent spikes 4 to 8 centimeters long. Growing with reddish to light green stems over one meter long, it forms dense underwater vegetation with distinctive finely dissected leaves. Its submersed leaves are intricately divided, featuring more than 28 narrow linear segments less than 10 millimeters long, arranged in uniform spacing throughout each leaf. This aggressive aquatic plant can quickly colonize water bodies, forming thick underwater mats that disrupt native ecosystems.
Identification and appearance
Key characters: 5 sympatric species; high segment count (≥28) and uniform arrangement are key
Habitat and range
Habitat: Uncommon. Ditches, lake margins
Elevation: < 2080 m
California counties: San Mateo, San Bernardino, Yolo, Riverside, Lassen, Los Angeles, San Diego, San Luis Obispo, Imperial, Sonoma, Sacramento, San Joaquin, Glenn, Yuba, Contra Costa, Napa, El Dorado, Placer, Alameda, Merced, Shasta, Solano, Plumas, Modoc, Marin, Santa Clara, Butte, Colusa, San Francisco, Humboldt, Kern, Santa Barbara
Outside California: to British Columbia, eastern Canada, eastern United States, native to Eurasia, northern Africa
Bloom period
Myriophyllum spicatum blooms Jul-Sep.
Conservation status
Cal-IPC Yes
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 spicatum native to California?
No. Myriophyllum spicatum is not native to California (recorded as not native).
When does Myriophyllum spicatum bloom?
Myriophyllum spicatum blooms Jul-Sep.
Where in California does Myriophyllum spicatum grow?
Myriophyllum spicatum occurs in San Mateo, San Bernardino, Yolo, Riverside, Lassen, Los Angeles, San Diego, San Luis Obispo and other counties, at elevations of < 2080 m.
What plant family does Myriophyllum spicatum belong to?
Myriophyllum spicatum is in the Haloragaceae family, genus Myriophyllum.
Is Myriophyllum spicatum invasive in California?
Myriophyllum spicatum is listed by Cal-IPC with an invasiveness rating of Yes.
Related species
Other California species in the same genus, family, or bioregion.
- Myriophyllum verticillatum — Whorled water-milfoil
- Myriophyllum aquaticum — Parrot's feather
- Myriophyllum hippuroides — Western water-milfoil
- Myriophyllum quitense — Andean water-milfoil
- Myriophyllum sibiricum — Siberian water-milfoil
- Myriophyllum sp. — Water-milfoil
- Haloragaceae sp. — Water-milfoil family
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.