The lists of Colorado's Noxious Weeds are located in the below table. To view more about a specific weed click on the name in blue text. If a plant name does not have a link this is because a plant plan or assessment has not been completed. Noxious Weed List
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List A Species in Colorado that are designated by the Commissioner for eradication.
List B Species are species for which the Commissioner, in consultation with the state noxious weed advisory committee, local governments, and other interested parties, develops and implements state noxious weed management plans designed to stop the continued spread of these species.
List C Species are species for which the Commissioner, in consultation with the state noxious weed advisory committee, local governments, and other interested parties, will develop and implement state noxious weed management plans designed to support the efforts of local governing bodies to facilitate more effective integrated weed management on private and public lands. The goal of such plans will not be to stop the continued spread of these species but to provide additional education, research, and biological control resources to jurisdictions that choose to require management of List C species.
Watch List Species that have been determined to pose a potential threat to the agricultural productivity and environmental values of the lands of the state. The Watch List is intended to serve advisory and educational purposes only. Its purpose is to encourage the identification and reporting of these species to the Commissioner in order to facilitate the collection of information to assist the Commissioner in determining which species should be designated as noxious weeds. PrintableColorado Watch List.
Download the noxious weed identificationmobile appforIOSandAndroid.
List A Species
Not Known In Colorado | Less Than 10 Known Populations|More Than 10 Populations in Colorado
Not Known in Colorado
Camelthorn
Alhagi pseudalhagi
Common crupina
Crupina vulgaris
Giant salvinia
Salvinia molesta
Hydrilla
Hydrilla verticillata
Medusahead
Taeniatherum caput-medusae
Parrotfeather
Myriophyllum aquaticum
Less Than 10 Known Populations
African rue
Peganum harmala
Dyer's woad
Isatis tinctoria
Elongated mustard
Brassica elongata
Flowering rush
Butomus umbellatus
Meadow knapweed
Centaurea x moncktonii
Rush skeletonweed
Chondrilla juncea
Tansy ragwort
Senecio jacobaea
Yellow starthistle
Centaurea solstitialis
More Than 10 Populations in Colorado
Cypress spurge
Euphorbia cyparissias
Giant reed
Arundo donax
Hairy willow-herb
Epilobium hirsutum
Knotweeds
Japanese, Giant, and Bohemian
Mediterranean sage
Salvia aethiopis
Myrtle spurge
Euphorbia myrsinites
Orange hawkweed
Hieracium aurantiacum
List B Species
Absinth wormwood
Artemisia absinthium
Black henbane
Hyoscyamus niger
Bouncingbet
Saponaria officinalis
Bull thistle
Cirsium vulgare
Canada thistle
Cirsium arvense
Chinese clematis
Clematis orientalis
Common tansy
Tanacetum vulgare
Common teasel
Dipsacus fullonum
Cutleaf teasel
Dipsacus laciniatus
Dalmatian toadflax
Linaria dalmatica & genistifolia
Dame's rocket
Hesperis matronalis
Diffuse knapweed
Centaurea diffusa
Eurasian watermilfoil
Myriophyllum spicatum
Hoary cress
Lepidium draba
Houndstongue
Cynoglossum officinale
Hybrid knapweed
Centaurea x psammogena = C. stoebe x C. diffusa
Hybrid toadflax
Linaria vulgaris x L. dalmatica
Jointed goatgrass
Aegilops cylindrica
Leafy spurge
Euphorbia esula
Mayweed chamomile
Anthemis cotula
Moth mullein
Verbascum blattaria
Musk thistle
Carduus nutans
Oxeye daisy
Leucanthemum vulgare
Perennial pepperweed
Lepidium latifolium
Plumeless thistle
Carduus acanthoides
Russian knapweed
Acroptilon repens
Russian-olive
Elaeagnus angustifolia
Salt cedar
Tamarix chinensis, T. parviflora, and T.
Scentless chamomile
Tripleurospermum inodorum
Scotch thistle
Onopordum acanthium
Spotted knapweed
Centaurea stoebe
Sulfur cinquefoil
Potentilla recta
Wild caraway
Carum carvi
Yellow nutsedge
Cyperus esculentus
Yellow toadflax
Linaria vulgaris
List C Species
Bulbous bluegrass
Poa bulbosa
Chicory
Cichorium intybus
Common burdock
Arctium minus
Common mullein
Verbascum thapsus
Common St. Johnswort
Hypericum perforatum
Downy brome
Bromus tectorum
Field bindweed
Convolvulus arvensis
Halogeton
Halogeton glomeratus
Johnsongrass
Sorghum halepense
Perennial sowthistle
Sonchus arvensis
Poison hemlock
Conium maculatum
Puncturevine
Tribulus terrestris
Quackgrass
Elymus repens
Redstem filaree
Erodium cicutarium
Velvetleaf
Abutilon theophrasti
Wild-proso millet
Panicum miliaceum
Watch List Species
Baby's breath
Gypsophila paniculata
Caucasian bluestem
Bothriochloa bladhii
Common bugloss
Anchusa officinalis
Common reed
Phragmites australis
Garlic mustard
Alliaria petiolata
Garden loosestrife
Lysimachia vulgaris
Himalayan blackberry
Rubus armeniacus
Hoary alyssum
Berteroa incana
Meadow hawkweed
Hieracium caespitosum
Onionweed
Asphodelus fistulosus
Siberian elm
Ulmus pumila
Scotch broom
Cytisus scoparius
Swainsonpea
Sphaerophysa salsula
Syrian beancaper
Zygophyllum fabago
Tree of Heaven
Ailanthus altissima
Ventenata grass
Ventenata dubia
White bryony
Bryonia alba
Yellow bluestem
Bothriochloa ischaemum
Yellow flag iris
Iris pseudacorus