Ezina · A field manual for plant care · Contiguous U.S.Vol. I · Ed. 2027 · Proof copy

Invasive plants regulated in Idaho

Idaho lists 66 plants as noxious weeds under IDAPA 02.06.09.220. The table below reproduces that list in full, showing each plant's status in the state's own words. Idaho's list is an agricultural noxious-weed law, which governs control and spread on farmland and rights of way rather than what a nursery may sell.

Compiled from the rule itself, retrieved July 20, 2026. Law changes; if you spot a listing we have wrong or stale, tell us at [email protected].

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2 of these plants are native to part of the United States, marked US native below. Nativity is regional. Black locust is native to the Appalachians and regulated in New England; Palmer amaranth is native to the Southwest and listed as an agricultural weed in the Corn Belt. A listing tells you what Idaho regulates, not where a plant belongs. The county checker answers the second question.

Regulated and invasive are two different findings, and this page shows them separately. 56 of the 66 plants below carry both: Idaho names them in statute and GRIIS lists them as invasive in the United States. The other 10 are regulated by Idaho without appearing on that register. The reverse is far more common still: most plants GRIIS calls invasive are named in no state’s statute at all and are sold freely, so an absent chip is never a clean bill of health.

Plant Scientific name Status Idaho’s determination
Black Henbane Hyoscyamus niger Listed Invasive Idaho lists Black Henbane under “Containment.”
Blood Grass Imperata cylindrica Listed Invasive Idaho lists Blood Grass under “EDRR.”Plant instead: Douglas' Sedge, Little Green Sedge, California Damsonium
Bohemian Knotweed Polygonum x bohemicum Listed Idaho lists Bohemian Knotweed under “Containment.”
Brazilian Waterweed Egeria densa Listed Invasive Idaho lists Brazilian Waterweed under “EDRR.”Plant instead: Star Sedge, Geyer's Sedge, Inland Sedge
Broadleaved Pepperweed Lepidium latifolium Listed Invasive Idaho lists Broadleaved Pepperweed under “Control.”
Butter and Eggs Linaria vulgaris Listed Invasive Idaho lists Butter and Eggs under “Control.”
Canada Thistle Cirsium arvense Listed Invasive Idaho lists Canada Thistle under “Control.”
Carolina Fanwort US native Cabomba caroliniana Listed Idaho lists Carolina Fanwort under “EDRR.”Plant instead: Star Sedge, Geyer's Sedge, Inland Sedge
Common Crupina Crupina vulgaris Listed Invasive Idaho lists Common Crupina under “Containment.”
Common Frogbit Hydrocharis morsus-ranae Listed Invasive Idaho lists Common Frogbit under “EDRR.”
Common Reed Phragmites australis Listed Idaho lists Common Reed under “Containment.”
Common Viper's Bugloss Echium vulgare Listed Invasive Idaho lists Common Viper's Bugloss under “Containment.”
Common Water Hyacinth Eichhornia crassipes Listed Invasive Idaho lists Common Water Hyacinth under “EDRR.”Plant instead: Wavyleaf Indian Paintbrush, Harsh Indian Paintbrush, Desert Centaury
Curly Pondweed Potamogeton crispus Listed Invasive Idaho lists Curly Pondweed under “Control.”
Dalmatian Toadflax Linaria dalmatica Listed Invasive Idaho lists Dalmatian Toadflax under “Control.”
Diffuse Knapweed Centaurea diffusa Listed Invasive Idaho lists Diffuse Knapweed under “Control.”
Dyer's Woad Isatis tinctoria Listed Invasive Idaho lists Dyer's Woad under “Containment.”
Eurasian Watermilfoil Myriophyllum spicatum Listed Invasive Idaho lists Eurasian Watermilfoil under “Containment.”
Feathered Mosquitofern Azolla pinnata Listed Invasive Idaho lists Feathered Mosquitofern under “EDRR.”
Field Bindweed Convolvulus arvensis Listed Invasive Idaho lists Field Bindweed under “Control.”
Field Sowthistle Sonchus arvensis Listed Invasive Idaho lists Field Sowthistle under “Containment.”
Flowering Rush Butomus umbellatus Listed Invasive Idaho lists Flowering Rush under “Containment.”Plant instead: Showy Milkweed, Desert Sweet, Western Water Hemlock
Giant Hogweed Heracleum mantegazzianum Listed Invasive Idaho lists Giant Hogweed under “EDRR.”
Giant Knotweed Polygonum sachalinense Listed Invasive Idaho lists Giant Knotweed under “Containment.”
Gypsyflower Cynoglossum officinale Listed Invasive Idaho lists Gypsyflower under “Control.”
Hardheads Acroptilon repens Listed Invasive Idaho lists Hardheads under “Containment.”
Hoary Alyssum Berteroa incana Listed Invasive Idaho lists Hoary Alyssum under “Control.”
Iberian Knapweed Centaurea iberica Listed Idaho lists Iberian Knapweed under “EDRR.”
Japanese Knotweed Polygonum cuspidatum Listed Idaho lists Japanese Knotweed under “Containment.”
Johnsongrass Sorghum halepense Listed Invasive Idaho lists Johnsongrass under “Containment.”
Jointed Goatgrass Aegilops cylindrica Listed Invasive Idaho lists Jointed Goatgrass under “Control.”
Kariba-Weed Salvinia molesta Listed Invasive Idaho lists Kariba-Weed under “EDRR.”
Leafy Spurge Euphorbia esula Listed Invasive Idaho lists Leafy Spurge under “Control.”
Matgrass Nardus stricta Listed Invasive Idaho lists Matgrass under “Containment.”
Meadow Hawkweed Hieracium caespitosum Listed Invasive Idaho lists Meadow Hawkweed under “Containment.”
Meadow Knapweed Centaurea debeauxii Listed Invasive Idaho lists Meadow Knapweed under “Containment.”
Mediterranean Sage Salvia aethiopis Listed Invasive Idaho lists Mediterranean Sage under “Containment.”
Nodding Plumeless Thistle Carduus nutans Listed Invasive Idaho lists Nodding Plumeless Thistle under “Containment.”
Orange Hawkweed Hieracium aurantiacum Listed Invasive Idaho lists Orange Hawkweed under “Containment.”
Ornamental Jewelweed Impatiens glandulifera Listed Invasive Idaho lists Ornamental Jewelweed under “EDRR.”
Oxeye Daisy Leucanthemum vulgare Listed Invasive Idaho lists Oxeye Daisy under “Control.”
Parrot Feather Watermilfoil Myriophyllum aquaticum Listed Invasive Idaho lists Parrot Feather Watermilfoil under “Containment.”Plant instead: Narrowleaf Water Plantain, Douglas' Sedge, Little Green Sedge
Poison Hemlock Conium maculatum Listed Invasive Idaho lists Poison Hemlock under “Control.”
Professor-Weed Galega officinalis Listed Invasive Idaho lists Professor-Weed under “EDRR.”
Puncturevine Tribulus terrestris Listed Invasive Idaho lists Puncturevine under “Control.”
Purple Loosestrife Lythrum salicaria Listed Invasive Idaho lists Purple Loosestrife under “Control.”Plant instead: Showy Milkweed, Desert Sweet, Western Water Hemlock
Queen-Devil Hawkweed Hieracium glomeratum Listed Idaho lists Queen-Devil Hawkweed under “EDRR.”
Red Star-Thistle Centaurea calcitrapa Listed Invasive Idaho lists Red Star-Thistle under “EDRR.”
Rush Skeletonweed Chondrilla juncea Listed Invasive Idaho lists Rush Skeletonweed under “Control.”
Scotch Broom Cytisus scoparius Listed Invasive Idaho lists Scotch Broom under “Containment.”Plant instead: Desert Sweet, Silky Lupine, Common Cowparsnip
Scotch Cottonthistle Onopordum acanthium Listed Invasive Idaho lists Scotch Cottonthistle under “Control.”
Small Bugloss Anchusa arvensis Listed Idaho lists Small Bugloss under “Containment.”
Spiny Plumeless Thistle Carduus acanthoides Listed Invasive Idaho lists Spiny Plumeless Thistle under “Control.”
Spotted Knapweed Centaurea stoebe Listed Invasive Idaho lists Spotted Knapweed under “Control.”
Spring Milletgrass Milium vernale Listed Idaho lists Spring Milletgrass under “Control.”
Squarrose Knapweed Centaurea virgata Listed Idaho lists Squarrose Knapweed under “EDRR.”
Stinking Willie Senecio jacobaea Listed Invasive Idaho lists Stinking Willie under “Control.”
Syrian Beancaper Zygophyllum fabago Listed Invasive Idaho lists Syrian Beancaper under “EDRR.”
Tall Hawkweed Hieracium piloselloides Listed Invasive Idaho lists Tall Hawkweed under “EDRR.”
Twoleaf Watermilfoil US native Myriophyllum heterophyllum Listed Idaho lists Twoleaf Watermilfoil under “EDRR.”
Water Chestnut Trapa natans Listed Invasive Idaho lists Water Chestnut under “EDRR.”Plant instead: Narrowleaf Water Plantain, Douglas' Sedge, Little Green Sedge
Waterthyme Hydrilla verticillata Listed Invasive Idaho lists Waterthyme under “EDRR.”Plant instead: Star Sedge, Geyer's Sedge, Inland Sedge
White Bryony Bryonia alba Listed Invasive Idaho lists White Bryony under “Control.”
Whitetop Cardaria draba Listed Invasive Idaho lists Whitetop under “Control.”
Yellow Floatingheart Nymphoides peltata Listed Invasive Idaho lists Yellow Floatingheart under “EDRR.”Plant instead: Wavyleaf Indian Paintbrush, Harsh Indian Paintbrush, Desert Centaury
Yellow Star-Thistle Centaurea solstitialis Listed Invasive Idaho lists Yellow Star-Thistle under “Control.”

What the tags mean

Prohibited Restricted Listed

A legal status. Idaho names the plant in statute. Under a nursery rule that means it may not be sold, propagated, or moved; under an agricultural weed law it means landowners must control it. The cited rule says which, in Idaho’s own words, in the last column.

Invasive

An ecological finding, and a different question from the law. GRIIS — the Global Register of Introduced and Invasive Species — lists the plant as invasive in the United States. Most invasive plants carry no state listing at all and are sold freely, so a plant without this tag is not thereby safe, and a plant without a legal chip is not thereby harmless.

Where this comes from

Idaho listings
IDAPA 02.06.09.220. Read the rule.
Invasive status
GRIIS, the Global Register of Introduced and Invasive Species, via GBIF. A scientific register with no legal force; it is cited separately from the statute above because the two disagree far more often than they agree.
Status wording
Each determination is written as a sentence, with Idaho’s own term for the plant reproduced verbatim inside it. The Prohibited / Restricted / Listed chips are Ezina’s normalisation across 42 states and are not the legal term.
Nativity
USDA PLANTS county distribution layer, surfaced through the county checker.

Regulated next door, but not in Idaho

Plants that two or more states bordering Idaho regulate, and Idaho does not. A listing is a legal act rather than an ecological one, so a plant can be a documented problem here and still be sold here.

Questions

What plants are illegal to sell in Idaho?

Idaho's list is an agricultural noxious-weed law, which governs control and spread on farmland and rights of way rather than what a nursery may sell. 66 plants are named under IDAPA 02.06.09.220. A noxious-weed listing does not automatically ban nursery sale, so check the rule itself before assuming a plant cannot be bought or sold.

Is my plant invasive in Idaho?

Search the table on this page, or enter the plant's name in Ezina's checker to get its Idaho status alongside whether USDA records it as native to your specific county. Every answer links the record it came from.

Does a plant missing from this list mean it is safe to plant in Idaho?

No. This page reproduces what Idaho regulates, and a state list is a legal instrument rather than an ecological verdict. Plenty of plants spread aggressively without ever being listed, and states add species years after the problem is documented.

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