PlantLegitColorado: invasive & noxious plant laws
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Under the Colorado Noxious Weed Act, C.R.S. § 35-5.5-104.5, it is unlawful to intentionally introduce, cultivate, sell or offer for sale any designated state noxious weed, or knowingly allow one to grow in violation of the Act or its rules. Exceptions cover sanctioned research, activities the Commissioner permits and approved reclamation plans. The Commissioner's rules (8 CCR 1206-2) sort the species into List A (eradicate), List B (stop the spread) and List C (local management). The CDA Watch List is advisory and is not shown here. Lists transcribed from the Colorado Department of Agriculture's species page.
Official sources
- C.R.S. § 35-5.5-104.5 (sale/cultivation ban)
- Colorado Dept. of Agriculture — Noxious weed species
- Federal Noxious Weed List, 7 CFR § 360.200 (USDA APHIS) — applies in every state
List A noxious weed (8 CCR 1206-2) — statewide eradication (25)
| Scientific name | Common name / notes |
|---|---|
| Alhagi pseudalhagi | camelthorn |
| Crupina vulgaris | common crupina |
| Salvinia molesta | giant salvinia |
| Hydrilla verticillata | hydrilla |
| Taeniatherum caput-medusae | medusahead |
| Myriophyllum aquaticum | parrotfeather |
| Centaurea virgata | squarrose knapweed |
| Ventenata dubia | ventenata grass |
| Peganum harmala | African rue |
| Isatis tinctoria | Dyer's woad |
| Brassica elongata | elongated mustard |
| Butomus umbellatus | flowering rush |
| Centaurea x moncktonii | meadow knapweed |
| Chondrilla juncea | rush skeletonweed |
| Senecio jacobaea | tansy ragwort |
| Centaurea solstitialis | yellow starthistle |
| Euphorbia cyparissias | Cypress spurge |
| Arundo donax | giant reed |
| Epilobium hirsutum | hairy willow-herb |
| Fallopia japonica, F. sachalinensis, F. x bohemica (Reynoutria japonica, R. sachalinensis, R. x bohemica) | Japanese, giant and Bohemian knotweeds |
| Salvia aethiopis | Mediterranean sage |
| Euphorbia myrsinites | myrtle spurge |
| Hieracium aurantiacum | orange hawkweed |
| Lythrum salicaria | purple loosestrife |
| Iris pseudacorus | yellow flag iris |
List B noxious weed (8 CCR 1206-2) — managed to stop spread (35)
| Scientific name | Common name / notes |
|---|---|
| Artemisia absinthium | absinth wormwood |
| Hyoscyamus niger | black henbane |
| Saponaria officinalis | bouncingbet |
| Cirsium vulgare | bull thistle |
| Cirsium arvense | Canada thistle |
| Clematis orientalis | Chinese clematis |
| Tanacetum vulgare | common tansy |
| Dipsacus fullonum | common teasel |
| Dipsacus laciniatus | cutleaf teasel |
| Linaria dalmatica, L. genistifolia | Dalmatian toadflax |
| Hesperis matronalis | Dame's rocket |
| Centaurea diffusa | diffuse knapweed |
| Myriophyllum spicatum | Eurasian watermilfoil |
| Lepidium draba | hoary cress |
| Cynoglossum officinale | houndstongue |
| Centaurea x psammogena (C. stoebe x C. diffusa) | hybrid knapweed |
| Linaria vulgaris x L. dalmatica | hybrid toadflax |
| Aegilops cylindrica | jointed goatgrass |
| Euphorbia esula | leafy spurge |
| Anthemis cotula | mayweed chamomile |
| Verbascum blattaria | moth mullein |
| Carduus nutans | musk thistle |
| Leucanthemum vulgare | oxeye daisy |
| Lepidium latifolium | perennial pepperweed |
| Carduus acanthoides | plumeless thistle |
| Rhaponticum repens | Russian knapweed |
| Elaeagnus angustifolia | Russian olive |
| Tamarix chinensis, T. parviflora, T. ramosissima | salt cedar |
| Tripleurospermum inodorum | scentless chamomile |
| Onopordum acanthium | Scotch thistle |
| Centaurea stoebe ssp. micranthos | spotted knapweed |
| Potentilla recta | sulfur cinquefoil |
| Carum carvi | wild caraway |
| Cyperus esculentus | yellow nutsedge |
| Linaria vulgaris | yellow toadflax |
List C noxious weed (8 CCR 1206-2) — widespread; local management (18)
| Scientific name | Common name / notes |
|---|---|
| Poa bulbosa | bulbous bluegrass |
| Cichorium intybus | chicory |
| Arctium minus | common burdock |
| Verbascum thapsus | common mullein |
| Hypericum perforatum | common St. Johnswort |
| Bromus tectorum | cheatgrass |
| Convolvulus arvensis | field bindweed |
| Halogeton glomeratus | halogeton |
| Sorghum halepense | Johnsongrass |
| Sonchus arvensis | perennial sowthistle |
| Conium maculatum | poison hemlock |
| Tribulus terrestris | puncturevine |
| Elymus repens | quackgrass |
| Erodium cicutarium | redstem filaree |
| Ulmus pumila | Siberian elm |
| Ailanthus altissima | tree of heaven |
| Abutilon theophrasti | velvetleaf |
| Panicum miliaceum | wild-proso millet |
Check plants against Colorado 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.