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Colorado Noxious Weed List

List A Species If you find it, eradicate it.

List B Species Help stop the spread.

List C Species Widely distributed.

Watch List Species Report to EDDMapS! More information needed to assess the threat. Colorado Watch List - Pocket Guide   

Printable: Noxious Weed List sorted by Common Name and by Scientific Name.

Need Help Identifying A Weed?

Contact your County Weed Manager or Local CSU Extension Agent

 

List A Species

Not Known In CO | Fewer Than 10 Known Populations | More Than 10 Populations

Not Known In Colorado

Camelthorn
Camelthorn
Alhagi pseudalhagi
Common crupina
Common crupina
Crupina vulgaris
Giant salvinia
Giant salvinia
Salvinia molesta
Hydrilla
Hydrilla
Hydrilla verticillata
Medusahead
Medusahead
Taeniatherum caput-medusae
Parrotfeather
Parrotfeather
Myriophyllum aquaticum
Squarrose knapweed
Squarrose knapweed
Centaurea virgata
Ventenata grass
Ventenata grass
Ventenata dubia
 

Fewer Than 10 Known Populations

African rue
African rue
Peganum harmala
Dyer's woad
Dyer's woad
Isatis tinctoria
Elongated mustard
Elongated mustard
Brassica elongata
Flowering rush
Flowering rush
Butomus umbellatus
Meadow knapweed
Meadow knapweed
Centaurea x moncktonii
Rush skeletonweed
Rush skeletonweed
Chondrilla juncea
Tansy ragwort
Tansy ragwort
Senecio jacobaea
Yellow starthistle
Yellow starthistle
Centaurea solstitialis
 

More Than 10 Populations in Colorado

Cypress spurge
Cypress spurge
Euphorbia cyparissias
Giant reed
Giant reed
Arundo donax
Hairy willow-herb
Hairy willow-herb
Epilobium hirsutum
Japanese, Giant, and Bohemian knotweed
Knotweeds
Japanese, Giant, and Bohemian
Mediterranean sage
Mediterranean sage
Salvia aethiopis
Myrtle spurge
Myrtle spurge
Euphorbia myrsinites
Orange hawkweed
Orange hawkweed
Hieracium aurantiacum
Purple loosestrife
Purple loosestrife
Lythrum salicaria
Yellow flag iris
Yellow flag iris
Iris pseudacorus
 

List B Species

Absinth wormwood
Absinth wormwood
Artemisia absinthium
Black henbane
Black henbane
Hyoscyamus niger
Bouncingbet
Bouncingbet
Saponaria officinalis
Bull thistle
Bull thistle
Cirsium vulgare
Canada thistle
Canada thistle
Cirsium arvense
Chinese clematis
Chinese clematis
Clematis orientalis
Common tansy
Common tansy
Tanacetum vulgare
Common teasel
Common teasel
Dipsacus fullonum
Cutleaf teasel
Cutleaf teasel
Dipsacus laciniatus
Dalmatian toadflax
Dalmatian toadflax
Linaria dalmatica & genistifolia
Dame's rocket
Dame's rocket
Hesperis matronalis
Diffuse knapweed
Diffuse knapweed
Centaurea diffusa
Eurasian watermilfoil
Eurasian watermilfoil
Myriophyllum spicatum
Hoary cress
Hoary cress
Lepidium draba
Houndstongue
Houndstongue
Cynoglossum officinale
Hybrid knapweed
Hybrid knapweed
Centaurea x psammogena = C. stoebe x C. diffusa
Hybrid toadflax
Hybrid toadflax
Linaria vulgaris x L. dalmatica
Jointed goatgrass
Jointed goatgrass
Aegilops cylindrica
Leafy spurge
Leafy spurge
Euphorbia esula
Mayweed chamomile
Mayweed chamomile
Anthemis cotula
Moth mullein
Moth mullein
Verbascum blattaria
Musk thistle
Musk thistle
Carduus nutans
Oxeye daisy
Oxeye daisy
Leucanthemum vulgare
Perennial pepperweed
Perennial pepperweed
Lepidium latifolium
Plumeless thistle
Plumeless thistle
Carduus acanthoides
Russian knapweed
Russian knapweed
Rhaponticum repens
Russian olive
Russian olive
Elaeagnus angustifolia
Tamarisk / Saltcedar
Salt cedar
Tamarix chinensis, T. parviflora, and  T. ramosissima
Scentless chamomile
Scentless chamomile
Tripleurospermum inodorum
Scotch thistle
Scotch thistle
Onopordum acanthium
Spotted and hybrid knapweed
Spotted knapweed
Centaurea stoebe ssp. micranthos
Sulfur cinquefoil
Sulfur cinquefoil
Potentilla recta
Wild caraway
Wild caraway
Carum carvi
Yellow nutsedge
Yellow nutsedge
Cyperus esculentus
Yellow hybrid toadflax
Yellow toadflax
Linaria vulgaris
 

List C Species

Chicory
Chicory
Cichorium intybus
Common burdock
Common burdock
Arctium minus
Common mullein
Common mullein
Verbascum thapsus
Common St. Johnswort
Common St. Johnswort
Hypericum perforatum
Downy brome
Downy brome
Bromus tectorum
Field bindweed
Field bindweed
Convolvulus arvensis
Halogeton
Halogeton
Halogeton glomeratus
Johnsongrass
Johnsongrass
Sorghum halepense
Perennial sowthistle
Perennial sowthistle
Sonchus arvensis
Poison hemlock
Poison hemlock
Conium maculatum
Puncturevine
Puncturevine
Tribulus terrestris
Quackgrass
Quackgrass
Elymus repens
Redstem filaree
Redstem filaree
Erodium cicutarium
Siberian elm
Siberian elm
Ulmus pumila
Tree of heaven
Tree of Heaven
Ailanthus altissima
Velvetleaf
Velvetleaf
Abutilon theophrasti
Wild proso millet
Wild-proso millet
Panicum miliaceum
 

Watch List Species

Baby's breath
Baby's breath
Gypsophila paniculata
Caucasian bluestem
Caucasian bluestem
Bothriochloa bladhii
Common bugloss
Common bugloss
Anchusa officinalis
Common reed
Common reed
Phragmites australis
Garlic mustard
Garlic mustard
Alliaria petiolata
Garden loosestrife
Garden loosestrife
Lysimachia vulgaris
Himalayan blackberry
Himalayan blackberry
Rubus armeniacus
Hoary Allysum
Hoary alyssum
Berteroa incana
Meadow hawkweed
Meadow hawkweed
Hieracium caespitosum
Onionweed
Onionweed
Asphodelus fistulosus
Closeup of a purple flower of the perennial sweet pea
Perennial Sweet Pea
Lathyrus latifolius
Scotch broom
Scotch broom
Cytisus scoparius
Swainsonpea
Swainsonpea
Sphaerophysa salsula
Syrian beancaper
Syrian beancaper
Zygophyllum fabago
Tall oatgrass closeup
Tall Oatgrass
Arrhenatherum elatius
White bryony
White bryony
Bryonia alba
Yellow bluestem
Yellow bluestem
Bothriochloa ischaemum
Yellow mignonette on a hillside
Yellow mignonette
Reseda lutea