Noxious Weed Species ID

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.

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.
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List A Species

Not Known In Colorado | Less Than 10 Known Populations|More Than 10 Populations in Colorado

Not Known in Colorado


Alhagi pseudalhagi 

Common Crupina

Common crupina
Crupina vulgaris

Giant Salvinia

Giant salvinia
Salvinia molesta


Hydrilla verticillata


Taeniatherum caput-medusae


Myriophyllum aquaticum

Squarrose Knapweed

Squarrose knapweed
Centaurea virgata 

Less Than 10 Known Populations

African Rue

African rue
Peganum harmala

Dyers 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 

Bohemian Knotweed

Japanese, Giant, and Bohemian 

Mediterranean Sage

Mediterranean sage
Salvia aethiopis 

Myrtle Spurge

Myrtle spurge
Euphorbia myrsinites 

Orange Hawkweed

Orange hawkweed
Hieracium aurantiacum 


Purple loosestrife
Lythrum salicaria 

List B Species

Absinth Wormwood

Absinth wormwood
Artemisia absinthium 

Black Henbane

Black henbane
Hyoscyamus niger 

Bouncing Bet

Saponaria officinalis 


Bull thistle
Cirsium vulgare


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

Dalmation Toadflax

Dalmatian toadflax
Linaria dalmatica & genistifolia

Dames Rocket

Dame's rocket
Hesperis matronalis

Diffuse Knapweed

Diffuse knapweed
Centaurea diffusa

Eurasian Watermilfoil

Eurasian watermilfoil
Myriophyllum spicatum

Hoary Cress

Hoary cress
Lepidium draba


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
Euphorbia esula

Mayweed Chamomile

Mayweed chamomile
Anthemis cotula

Moth Mullein

Moth mullein
Verbascum blattaria


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
Acroptilon repens


Elaeagnus angustifolia

Salt Cedar

Salt cedar
Tamarix chinensis, T. parviflora, and  T.

Scentless Chamomile

Scentless chamomile
Tripleurospermum inodorum

Scotch Thistle

Scotch thistle
Onopordum acanthium

Spotted Knapweed

Spotted knapweed
Centaurea stoebe 

Sulfur Cinguefoil

Sulfur cinquefoil
Potentilla recta

Wild Caraway

Wild caraway
Carum carvi

Yellow Nutsedge

Yellow nutsedge
Cyperus esculentus

Yellow Toadflax

Yellow toadflax
Linaria vulgaris

List C Species

Bulbouse Bluegrass

Bulbous bluegrass
Poa bulbosa


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
Convolvulus arvensis


Halogeton glomeratus


Sorghum halepense

Perennial Sowthistle

Perennial sowthistle
Sonchus arvensis

Poison Hemlock

Poison hemlock
Conium maculatum


Tribulus terrestris


Elymus repens

Redstem Filaree

Redstem filaree
Erodium cicutarium


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

Onion weed

Asphodelus fistulosus

Siberian elm

Siberian elm
Ulmus pumila

Scotch Broom

Scotch broom
Cytisus scoparius


Sphaerophysa salsula

Syrian beancaper

Syrian beancaper
Zygophyllum fabago


Tree of Heaven
Ailanthus altissima


Ventenata grass
Ventenata dubia

White Bryony

White bryony
Bryonia alba

yellow bluestem

Yellow bluestem
Bothriochloa ischaemum

Yellow Flag Iris

Yellow flag iris
Iris pseudacorus