The Mission of the Yellowstone County Weed Department is to assist the public, private, and other government agencies to manage and control existing noxious weed infestations as well as to prevent new invasive species from infesting Yellowstone County.

HydrillaHydrilla verticillata

Photo from Montana Weed Control Association

Aquatic

Stem

Leaf

Branch

Branch

Patch

Photos from Montana Weed Control Association

Attribute	Information
Toxicity	Non-toxic.
Control	Drawdown of water levels, mechanical harvesters, biological and aquatic herbicide. Contact your County Weed District or local Applicator for more information.
Habitat	Springs, lakes, ponds, marshes, ditches and rivers.
Root	Extensive root system.
Leaf Shape	Small, lance-shaped with pointed tips.
Lifespan	Perennial; two years or longer.
Priority 3 Weed	Not a noxious weed, but a regulated plant; potential for significant negative economic and ecological impacts.
Similar Looking Plants	Brazilian waterweed and Elodea.
Important Information	Mainly reproduces and spreads by fragments; roots dormant and viable in the soil for up to eight years.