Myriophyllum spicatum

Eurasian water-milfoil, Eurasian Water-Milfoil

Family: Haloragaceae · Type: perennial · Not Native

Conservation status: Cal-IPC Yes

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.

Habitat: Uncommon. Ditches, lake margins

Bloom period: Jul-Sep

Elevation: < 2080 m

Bioregions: NCoRI, SNF, n SNH, GV, SnFrB, SCo, SnBr, PR, MP

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

Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Jepson eFlora, Cal-IPC, and more.