Missoula County Weed District & Extension

Weed Identification

What is a Noxious Weed?

Noxious weeds are defined as being any exotic plant species which may render land unfit for agriculture, forestry, livestock, wildlife or other beneficial uses or that may harm native plant communities.

Click here for plant definitions.

Click here to find out what weeds are in your area

Priority 1 Weeds:
These noxious weeds are currently not found in Missoula County. Management criteria include monitoring for their presence, prevention, education, mapping, and if found, eradication.

Curly Leaf PondweedCurly Leaf Pondweed Eurasian WatermilfoilEurasian Watermilfoil Flowering RushFlowering Rush Rush SkeletonweedRush Skeleton Weed
Scotch BroomScotch Broom Tansy Ragwort Tansy Ragwort Yellow StarthistleYellow Starthistle


Priority 2 Weeds:
These noxious weeds are small infestations, less than 1000 acres, and classified as "new invaders." These plants have the highest priority in Missoula County to keep them from spreading. Management criteria include prevention, education, early detection, mapping, and eradication. Landowner groups will be organized for each new invader weed species. Priority for controlling Knotweed complex and Tamarisk will be in the riparian areas. Control of these two plants grown as ornamentals will be voluntary by the homeowner. The Weed District will pay up to $100.00 towards their removal.

BluweedBlueweed Diffuse KnapweedDiffuse Knapweed Dyer's WoadDyer's Woad KnotweedKnotweed Complex
Meadow HawkweedMeadow Hawkweed Orange HawkweedOrange Hawkweed Perennial PepperweedPerennial Pepperweed Purple LoosestrifePurple Loosestrife
Russian KnapweedRussian Knapweed Tamarisk or Salt Cedar Tamarisk or Saltcedar Whitetop
Yellow Flag IrisYellowflag Iris


Priority 3 Weeds:
These noxious weeds are widespread infestations over 1000 acres. They are managed through organized cooperative landowner groups. Scattered infestations of Leafy spurge, Dalmatian toadflax, and Yellow toadflax outside the designated infestations will be
Priority 2.

Canada ThistleCanada Thistle Common TansyCommon Tansy Dalmatian ToadflaxDalmation Toadflax Field Bindweed
Field Bindweed
Hoary AlyssumHoary Alyssum HoundstongueHoundstongue Leafy SpurgeLeafy Spurge Oxeye DaisyOxeye Daisy
St. JohnswortSt. Johnswort Spotted KnapweedSpotted Knapweed Sulfur CinquefoilSulfur Cinquefoil Tall ButtercupTall Buttercup
Common ToadflaxYellow Toadflax


Regulated Species
The Montana Department of Agriculture has designated the following plants as "regulated" which means they cannot be sold or distributed.

CheatgrassCheatgrass HydrillaHydrilla Russian OliveRussian Olive