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Montana: invasive & noxious plant laws
New laws coming: several states phase in plant bans 2027–2030. See dates and sources →
Montana's statewide noxious weed list is set by the Department of Agriculture in ARM 4.5.206-4.5.210 under the County Noxious Weed Control Act (MCA 7-22-21). Landowners must manage listed noxious weeds under county weed district plans. The Priority 1 and 2 categories are management (control) categories; we did not find a statewide sale ban for them in the rules. Priority 3 regulated plants, such as Russian olive, are not noxious weeds but may not be intentionally spread or sold. Counties list additional weeds.
Official sources
Priority 1A noxious weed (ARM 4.5.206), control list — eradicate if found — not a sale ban (4)
| Scientific name | Common name / notes |
|---|
| Centaurea solstitialis | yellow starthistle |
| Isatis tinctoria | dyer's woad |
| Phragmites australis subsp. australis | common reed |
| Taeniatherum caput-medusae | medusahead |
Priority 1B noxious weed (ARM 4.5.207), control list — eradicate or contain — not a sale ban (7)
| Scientific name | Common name / notes |
|---|
| Reynoutria japonica (syn. Fallopia japonica, Polygonum cuspidatum) | Japanese knotweed |
| Reynoutria sachalinensis | giant knotweed |
| Reynoutria ×bohemica | Bohemian knotweed |
| Lythrum salicaria | purple loosestrife |
| Chondrilla juncea | rush skeletonweed |
| Cytisus scoparius | Scotch broom |
| Echium vulgare | blueweed |
Priority 2A noxious weed (ARM 4.5.208), control list — not a sale ban (12)
| Scientific name | Common name / notes |
|---|
| Senecio jacobaea (syn. Jacobaea vulgaris) | tansy ragwort |
| Hieracium caespitosum (syn. Pilosella caespitosa) | meadow hawkweed |
| Hieracium praealtum | meadow hawkweed complex |
| Hieracium floribundum | meadow hawkweed complex |
| Hieracium aurantiacum (syn. Pilosella aurantiaca) | orange hawkweed |
| Ranunculus acris | tall buttercup |
| Lepidium latifolium | perennial pepperweed |
| Iris pseudacorus | yellowflag iris |
| Myriophyllum spicatum | Eurasian watermilfoil |
| Butomus umbellatus | flowering rush |
| Rhamnus cathartica | common buckthorn |
| Ventenata dubia | ventenata |
Priority 2B noxious weed (ARM 4.5.209), control list — not a sale ban (17)
| Scientific name | Common name / notes |
|---|
| Cirsium arvense | Canada thistle |
| Convolvulus arvensis | field bindweed |
| Euphorbia esula | leafy spurge |
| Lepidium draba | whitetop |
| Rhaponticum repens | Russian knapweed |
| Centaurea stoebe | spotted knapweed |
| Centaurea diffusa | diffuse knapweed |
| Linaria dalmatica | Dalmatian toadflax |
| Hypericum perforatum | St. Johnswort |
| Potentilla recta | sulfur cinquefoil |
| Tanacetum vulgare | common tansy |
| Leucanthemum vulgare | oxeye daisy |
| Cynoglossum officinale | houndstongue |
| Linaria vulgaris | yellow toadflax |
| Tamarix spp. | saltcedar |
| Potamogeton crispus | curlyleaf pondweed |
| Berteroa incana | hoary alyssum |
Priority 3 regulated plant (ARM 4.5.210) — may not be intentionally spread or sold (5)
| Scientific name | Common name / notes |
|---|
| Bromus tectorum | cheatgrass |
| Hydrilla verticillata | hydrilla |
| Elaeagnus angustifolia | Russian olive |
| Egeria densa | Brazilian waterweed |
| Myriophyllum aquaticum | parrot feather watermilfoil |
Check plants against Montana law →
Informational only, not legal advice. Lists change; always check the official source linked above before you buy, sell, plant or move a plant. Lists checked 2026-10-14.
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