Noxious Weed Species

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. Printable Noxious Weed List.

List A species
List A species in Colorado that are designated by the Commissioner for eradication.

List B species
List B weed 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
List C weed 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
Watch List weed 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.  Colorado Watch List pdf file

List A Species

African Rue

African rue
Peganum harmala

 

Knotweed

Bohemian knotweed
Polygonum x bohemicum 

 

Camelthorn

Camelthorn
Alhagi pseudalhagi 

 

Common crupina

Common crupina
Crupina vulgaris 

Cypress spurge

Cypress spurge
Euphorbia cyparissias 

 

Dyers woad

Dyer's woad
Isatis tinctoria 

 

Elongated Mustard

Elongated mustard
Brassica elongata 

 

Knotweed

Giant knotweed
Polygonum sachalinense 

Giant reed

Giant reed
Arundo donax 

 

Giant salvinia

Giant salvinia
Salvinia molesta 

 

Hydrilla

Hydrilla
Hydrilla verticillata 

 

Knotweed

Japanese knotweed
Polygonum cuspidatum 

Meadow knapweed

Meadow knapweed
Centaurea pratensis 

 

Mediterranean sage

Mediterranean sage
Salvia aethiopis

 

Medusahead rye

Medusahead
Taeniatherum caput-medusae 

 

Myrtle spurge

Myrtle spurge
Euphorbia myrsinites 

Orange hawkweed

Orange hawkweed
Hieracium aurantiacum 

 

Purple loosestrife

Purple loosestrife
Lythrum salicaria 

 

Rush skeletonweed

Rush skeletonweed
Chondrilla juncea 

 

Squarrose knapweed

Squarrose knapweed
Centaurea virgata 

Tansy ragwort

Tansy ragwort
Senecio jacobaea

 

Yellow starthistle

Yellow starthistle
Centaurea solstitialis

       
List B Species

Absinth Wormwood

Absinth wormwood
Artemisia absinthium

 

Black henbane

Black henbane
Hyoscyamus niger

 

Bouncing bet

Bouncing bet
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

Corn chamomile

Corn chamomile
Anthemis arvensis

 

Cutleaf teasel

Cutleaf teasel
Dipsacus laciniatus

 

Dalmatian 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 
Cardaria draba

 

Houndstongue

Houndstongue 
Cynoglossum officinale

 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
Chrysanthemum leucanthemum

 

Perennial pepperweed

Perennial pepperweed
Lepidium latifolium

 

Plumless thistle

 Plumeless thistle
Carduus acanthoides

Quackgrass

Quackgrass 
Elytrigia repens

 

Russian knapweed

Russian knapweed
Acroptilon repens

 

Russian olive

Russian-olive
Elaeagnus angustifolia

 

Saltcedar

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

Scentless chamomile

Scentless chamomile
Matricaria perforata

 

Scotch thistle

Scotch thistle
Onopordum acanthium

 

Spotted knapweed

Spotted knapweed
Centaurea maculosa

 

Spurred anoda

Spurred Anoda
Anoda cristata 

Sulfur cinquefoil

Sulfur cinquefoil
Potentilla recta

 

Venice mallow

Venice mallow
Hibiscus trionum

 

Wild caraway

Wild caraway
Carum carvi

 

Yellow nutsedge

Yellow nutsedge
Cyperus esculentus

Yellow toadflax

Yellow toadflax 
Linaria vulgaris

           
List C Species

Bulbous bluegrass

Bulbous bluegrass
Poa bulbosa

 

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 © Clinton Shock

Halogeton
Halogeton glomeratus

Johnsongrass

Johnsongrass
Sorghum halepense

 

Perennial sowthistle

Perennial sowthistle
Sonchus arvensis

 

Poison hemlock

Poison hemlock
Conium maculatum

 

Puncturevine © Eric Coombs @ OR Dept of Ag

Puncturevine
Tribulus terrestris

Redstem filaree

Redstem filaree
Erodium cicutarium

 

Velvetleaf

Velvetleaf
Abutilon theophrasti

 

Wild-proso millet

Wild-proso millet
Panicum miliaceum

   
Watch List Species

Asian mustard © Lara Hartley 

Asian mustard 
Brassica tournefortii

 

Babys Breath © Richard Old 

Baby's breath
Gypsophila paniculata

 

Spiny_cocklebur_005 © John Randall 

Bathurst burr/
Spiney cocklebur

Xanthium spinosum

 

Brazilian_elodea_005 

Brazilian Elodea
Egeria densa

Common bugloss © J.S. Peterson  

Common bugloss
Anchusa officinalis

 

Common reed © Leslie Mehroff 

Common reed
Phragmites australis

 

Flowering rush © Louis Landry 

Flowering rush
Butomus umbellatus

 

Garlic mustard 

Garlic mustard 
Alliaria petiolata

Hairy willow-herb © Richard Old 

Hairy willow-herb 
Epilobium hirsutum

 

Himalayan blackberry © John Randall 

Himalayan blackberry 
Rubus armeniacus

 

Congongrass © Charles Bryson USDA 

Japanese blood grass/
cogongrass
  
Imperata cylindrical

 

Meadow hawkweed © Richard Old 

Meadow hawkweed 
Hieracium caespitosum

Onionweed © William Ciesla

Onionweed 
Asphodelus fistulosus

 

Parrotfeather_005

Parrotfeather 
Myriophyllum aquaticum

 

 Purple pampasgrass © John DiTomaso 

Purple Pampasgrass 
Cortideria jubata

 

Scotch broom © Eric Coombs

Scotch broom 
Cytisus scoparius

Sericea lespedeza © Dan Tenaglia  

Sericea lespedeza
Lespedeza cuneata

 

Swainsonpea © Richard Old 

Swainsonpea 
Sphaerophysa salsula

 

Syrian beancaper © Dell Clark 

Syrian beancaper 
Zygophyllum fabago

 

Water hyacinth © Chris Evans 

Water hyacinth 
Eichhornia crassipes

Water lettuce © Richard Old 

Water lettuce 
Pistia stratiotes

 

White bryony © Jan Samanek 

White bryony 
Bryonia alba

 

Whoolly distaff thistle © Joseph DiTomaso 

Woolly distaff thistle 
Carthamus lanatus

 

Yellow flag iris © Patty York 

Yellow flag iris 
Iris pseudacorus

Yellow_floatingheart_005 

Yellow floatingheart 
Nymphoides peltata

 

Yellowtuft_005 

Yellowtuft 
Alyssum murale & A. corsicum