Invasive plants regulated in Colorado (78 species, cited)

Invasive plants regulated in Colorado

Colorado lists 78 plants as noxious weeds under 8 CCR 1206-2. The table below reproduces that list in full, showing each plant's status in the state's own words. Colorado'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].

Regulated and invasive are two different findings, and this page shows them separately. 67 of the 78 plants below carry both: Colorado names them in statute and GRIIS lists them as invasive in the United States. The other 11 are regulated by Colorado 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	Colorado’s determination
Bohemian Knotweed	Polygonum x bohemicum	Prohibited	Colorado lists Bohemian Knotweed under “List A.”
Camelthorn	Alhagi maurorum	Prohibited Invasive	Colorado lists Camelthorn under “List A.”
Codlins and Cream	Epilobium hirsutum	Prohibited Invasive	Colorado lists Codlins and Cream under “List A.”
Common Crupina	Crupina vulgaris	Prohibited Invasive	Colorado lists Common Crupina under “List A.”
Creeping Spurge	Euphorbia myrsinites	Prohibited	Colorado lists Creeping Spurge under “List A.”
Cypress Spurge	Euphorbia cyparissias	Prohibited Invasive	Colorado lists Cypress Spurge under “List A.”Plant instead: Yerba Mansa, Douglas' Sedge, Chestnut Rush
Dyer's Woad	Isatis tinctoria	Prohibited Invasive	Colorado lists Dyer's Woad under “List A.”
Elongated Mustard	Brassica elongata	Prohibited	Colorado lists Elongated Mustard under “List A.”
Flowering Rush	Butomus umbellatus	Prohibited Invasive	Colorado lists Flowering Rush under “List A.”Plant instead: Showy Milkweed, Colorado Barberry, Blackbrush
Giant Knotweed	Polygonum sachalinense	Prohibited Invasive	Colorado lists Giant Knotweed under “List A.”
Giant Reed	Arundo donax	Prohibited Invasive	Colorado lists Giant Reed under “List A.”
Harmal Peganum	Peganum harmala	Prohibited Invasive	Colorado lists Harmal Peganum under “List A.”
Japanese Knotweed	Fallopia japonica (potentially invasive weed)	Prohibited Invasive	Colorado lists Japanese Knotweed under “List A.”
Kariba-Weed	Salvinia molesta	Prohibited Invasive	Colorado lists Kariba-Weed under “List A.”
Meadow Knapweed	Centaurea x moncktonii	Prohibited	Colorado lists Meadow Knapweed under “List A.”
Mediterranean Sage	Salvia aethiopis	Prohibited Invasive	Colorado lists Mediterranean Sage under “List A.”
Medusahead	Taeniatherum caput-medusae	Prohibited Invasive	Colorado lists Medusahead under “List A.”
North Africa Grass	Ventenata dubia	Prohibited Invasive	Colorado lists North Africa Grass under “List A.”
Orange Hawkweed	Hieracium aurantiacum	Prohibited Invasive	Colorado lists Orange Hawkweed under “List A.”
Paleyellow Iris	Iris pseudacorus	Prohibited Invasive	Colorado lists Paleyellow Iris under “List A.”Plant instead: Showy Milkweed, Colorado Barberry, Blackbrush
Parrot Feather Watermilfoil	Myriophyllum aquaticum	Prohibited Invasive	Colorado lists Parrot Feather Watermilfoil under “List A.”Plant instead: Narrowleaf Water Plantain, Yerba Mansa, Douglas' Sedge
Purple Loosestrife	Lythrum salicaria	Prohibited Invasive	Colorado lists Purple Loosestrife under “List A.”Plant instead: Showy Milkweed, Colorado Barberry, Blackbrush
Rush Skeletonweed	Chondrilla juncea	Prohibited Invasive	Colorado lists Rush Skeletonweed under “List A.”
Squarrose Knapweed	Centaurea virgata	Prohibited	Colorado lists Squarrose Knapweed under “List A.”
Stinking Willie	Senecio jacobaea	Prohibited Invasive	Colorado lists Stinking Willie under “List A.”
Waterthyme	Hydrilla verticillata	Prohibited Invasive	Colorado lists Waterthyme under “List A.”Plant instead: Star Sedge, Geyer's Sedge, Inland Sedge
Yellow Star-Thistle	Centaurea solstitialis	Prohibited Invasive	Colorado lists Yellow Star-Thistle under “List A.”
Absinthium	Artemisia absinthium	Listed Invasive	Colorado lists Absinthium under “List B.”
Black Henbane	Hyoscyamus niger	Listed Invasive	Colorado lists Black Henbane under “List B.”
Bouncingbet	Saponaria officinalis	Listed Invasive	Colorado lists Bouncingbet under “List B.”
Broadleaved Pepperweed	Lepidium latifolium	Listed Invasive	Colorado lists Broadleaved Pepperweed under “List B.”
Broomleaf Toadflax	Linaria genistifolia	Listed	Colorado lists Broomleaf Toadflax under “List B.”
Bulbous Bluegrass	Poa bulbosa	Listed Invasive	Colorado lists Bulbous Bluegrass under “List C.”
Bull Cottonthistle	Onopordum tauricum	Listed	Colorado lists Bull Cottonthistle under “List B.”
Bull Thistle	Cirsium vulgare	Listed Invasive	Colorado lists Bull Thistle under “List B.”
Butter and Eggs	Linaria vulgaris	Listed Invasive	Colorado lists Butter and Eggs under “List B.”
Canada Thistle	Cirsium arvense	Listed Invasive	Colorado lists Canada Thistle under “List B.”
Caraway	Carum carvi	Listed Invasive	Colorado lists Caraway under “List B.”
Cheatgrass	Bromus tectorum	Listed Invasive	Colorado lists Cheatgrass under “List C.”
Chicory	Cichorium intybus	Listed Invasive	Colorado lists Chicory under “List C.”
Common Mullein	Verbascum thapsus	Listed Invasive	Colorado lists Common Mullein under “List C.”
Common St. Johnswort	Hypericum perforatum	Listed Invasive	Colorado lists Common St. Johnswort under “List C.”
Cutleaf Teasel	Dipsacus laciniatus	Listed Invasive	Colorado lists Cutleaf Teasel under “List B.”
Dalmatian Toadflax	Linaria dalmatica	Listed Invasive	Colorado lists Dalmatian Toadflax under “List B.”
Dames Rocket	Hesperis matronalis	Listed Invasive	Colorado lists Dames Rocket under “List B.”Plant instead: Streambank Wild Hollyhock, Cascade Azalea, Black Raspberry
Diffuse Knapweed	Centaurea diffusa	Listed Invasive	Colorado lists Diffuse Knapweed under “List B.”
Eurasian Watermilfoil	Myriophyllum spicatum	Listed Invasive	Colorado lists Eurasian Watermilfoil under “List B.”
Field Bindweed	Convolvulus arvensis	Listed Invasive	Colorado lists Field Bindweed under “List C.”
Field Sowthistle	Sonchus arvensis	Listed Invasive	Colorado lists Field Sowthistle under “List C.”
Fuller's Teasel	Dipsacus fullonum	Listed	Colorado lists Fuller's Teasel under “List B.”
Gypsyflower	Cynoglossum officinale	Listed Invasive	Colorado lists Gypsyflower under “List B.”
Johnsongrass	Sorghum halepense	Listed Invasive	Colorado lists Johnsongrass under “List C.”
Jointed Goatgrass	Aegilops cylindrica	Listed Invasive	Colorado lists Jointed Goatgrass under “List B.”
Knapweed	Centaurea x psammogena	Listed Invasive	Colorado lists Knapweed under “List B.”
Leafy Spurge	Euphorbia esula	Listed Invasive	Colorado lists Leafy Spurge under “List B.”
Lenspod Whitetop	Cardaria chalepensis	Listed	Colorado lists Lenspod Whitetop under “List B.”
Lesser Burdock	Arctium minus	Listed Invasive	Colorado lists Lesser Burdock under “List C.”
Moth Mullein	Verbascum blattaria	Listed Invasive	Colorado lists Moth Mullein under “List B.”
Nodding Plumeless Thistle	Carduus nutans	Listed Invasive	Colorado lists Nodding Plumeless Thistle under “List B.”
Oriental Virginsbower	Clematis orientalis	Listed	Colorado lists Oriental Virginsbower under “List B.”
Oxeye Daisy	Leucanthemum vulgare	Listed Invasive	Colorado lists Oxeye Daisy under “List B.”
Poison Hemlock	Conium maculatum	Listed Invasive	Colorado lists Poison Hemlock under “List C.”
Proso Millet	Panicum miliaceum	Listed Invasive	Colorado lists Proso Millet under “List C.”
Puncturevine	Tribulus terrestris	Listed Invasive	Colorado lists Puncturevine under “List C.”
Quackgrass	Elymus repens	Listed Invasive	Colorado lists Quackgrass under “List C.”
Redstem Stork's Bill	Erodium cicutarium	Listed Invasive	Colorado lists Redstem Stork's Bill under “List C.”
Russian Olive	Elaeagnus angustifolia	Listed Invasive	Colorado lists Russian Olive under “List B.”Plant instead: Western Soapberry, Cerro Hawthorn, American Plum
Saltlover	Halogeton glomeratus	Listed Invasive	Colorado lists Saltlover under “List C.”
Scentless False Mayweed	Tripleurospermum perforatum	Listed Invasive	Colorado lists Scentless False Mayweed under “List B.”
Scotch Cottonthistle	Onopordum acanthium	Listed Invasive	Colorado lists Scotch Cottonthistle under “List B.”
Siberian Elm	Ulmus pumila	Listed Invasive	Colorado lists Siberian Elm under “List C.”Plant instead: Pinyon Pine, Bristlecone Pine, Narrowleaf Cottonwood
Spiny Plumeless Thistle	Carduus acanthoides	Listed Invasive	Colorado lists Spiny Plumeless Thistle under “List B.”
Stinking Chamomile	Anthemis cotula	Listed Invasive	Colorado lists Stinking Chamomile under “List B.”
Sulphur Cinquefoil	Potentilla recta	Listed Invasive	Colorado lists Sulphur Cinquefoil under “List B.”
Tansy	Tanacetum vulgare	Listed Invasive	Colorado lists Tansy under “List B.”
Tree of Heaven	Ailanthus altissima	Listed Invasive	Colorado lists Tree of Heaven under “List C.”Plant instead: Pinyon Pine, Bristlecone Pine, Narrowleaf Cottonwood
Velvetleaf	Abutilon theophrasti	Listed Invasive	Colorado lists Velvetleaf under “List C.”
Yellow Nutsedge	Cyperus esculentus	Listed	Colorado lists Yellow Nutsedge under “List B.”

What the tags mean

Prohibited Restricted Listed

A legal status. Colorado 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 Colorado’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

Colorado listings: 8 CCR 1206-2. 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 Colorado’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 Colorado

Plants that two or more states bordering Colorado regulate, and Colorado 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.

Maltese Star-Thistle Centaurea melitensis regulated in Arizona, New Mexico, Utah
Asian Mustard Brassica tournefortii regulated in Arizona, Utah
Common Reed Phragmites australis regulated in Nebraska, Utah
Hardheads Acroptilon repens regulated in Arizona, Utah
Red Star-Thistle Centaurea calcitrapa regulated in New Mexico, Utah
Saltcedar Tamarix ramosissima regulated in Nebraska, Utah
Sericea Lespedeza Lespedeza cuneata regulated in Kansas, Nebraska
Spotted Knapweed Centaurea stoebe regulated in Kansas, Utah
Spotted Knapweed Centaurea stoebe subsp. micranthos regulated in Nebraska, New Mexico

Questions

What plants are illegal to sell in Colorado?

Colorado'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. 78 plants are named under 8 CCR 1206-2. 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 Colorado?

Search the table on this page, or enter the plant's name in Ezina's checker to get its Colorado 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 Colorado?

No. This page reproduces what Colorado 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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