Hydrilla verticillata
Hydrilla
(c) mfeaver, some rights reserved (CC BY), uploaded by mfeaver · licence
Family: Hydrocharitaceae · Type: Herb · Not Native
Conservation status: Cal-IPC Yes
Hydrilla verticillata (Hydrilla) is a non-native California herb in the Hydrocharitaceae family, recognized by Monotypic genus; highly invasive aquatic species from Eurasia/Australia.
Hydrilla is a naturalized perennial herb found in northern and central Sierra Nevada foothills, Sacramento Valley, southern California coastal areas, and desert regions in canals, ponds, and lakes at elevations below 200 meters. Flowering from June to August, this aquatic plant produces small white flowers with spheric or cylindric structures. Growing with elongate, much-branched stems that root at nodes and can reach several centimeters tall, it forms dense underwater vegetation. Its leaves are distinctive, typically 4 to 8 per node, sessile, oblong, and coarsely serrate with sharp-pointed tips measuring 1 to 2 centimeters long. The plant produces small fusiform fruits approximately 5 to 6 millimeters in length, making it a persistent and adaptable aquatic invasive species.
Identification and appearance
Key characters: Monotypic genus; highly invasive aquatic species from Eurasia/Australia
Habitat and range
Habitat: Canals, ponds, lakes
Elevation: < 200 m
Outside California: southeastern and eastern United States, Central America, native to Eurasia, Australia
Bloom period
Hydrilla verticillata blooms Jun-Aug.
Conservation status
Cal-IPC Yes
How to tell it apart
vs Elodea: Hydrilla has 4-8 leaves per whorl consistently; Elodea has 2-3 leaves low on stem, 3-7 higher up.; vs Najas: Hydrilla has prickly bumps on leaf midrib; Najas midrib is smooth (teeth only on leaf edges).; vs Egeria: Hydrilla leaves are small (under 1.5 cm) with many per whorl; Egeria has much larger leaves (1.2-4 cm).; vs Ottelia: Hydrilla is submerged with whorled narrow leaves; Ottelia has floating rosettes and large showy flowers.; vs Limnobium: Hydrilla is completely submerged with whorled leaves; Limnobium has round floating leaves above water.
Frequently asked questions
Is Hydrilla verticillata native to California?
No. Hydrilla verticillata is not native to California (recorded as not native).
When does Hydrilla verticillata bloom?
Hydrilla verticillata blooms Jun-Aug.
What plant family does Hydrilla verticillata belong to?
Hydrilla verticillata is in the Hydrocharitaceae family, genus Hydrilla.
Is Hydrilla verticillata invasive in California?
Hydrilla verticillata is listed by Cal-IPC with an invasiveness rating of Yes.
What habitat does Hydrilla verticillata grow in?
Hydrilla verticillata grows in Canals, ponds, lakes.
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.