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 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. Printable Colorado Watch List.
 Download the noxious weed identication mobile app for IOS and Android


List A Species


African rue

Peganum harmala

Bohemian knotweed

Polygonum x bohemicum 

Camelthorn

Alhagi pseudalhagi

Common crupina

Crupina vulgaris

Cypress spurge

Euphorbia cyparissias

Dyer's woad

Isatis tinctoria

Elongated mustard

Brassica elongata

Flowering rush

Butomus umbellatus

Giant knotweed
Polygonum sachalinense

Giant reed

Arundo donax

Giant salvinia

Salvinia molesta
Hairy willow-herb
Hairy willow-herb

Epilobium hirsutum

Hydrilla
Hydrilla verticillata

Japanese knotweed
Polygonum cuspidatum

Meadow knapweed
Centaurea pratensis

Mediterranean sage
Salvia aethiopis

Medusahead
Taeniatherum caput-medusae

Myrtle spurge
Euphorbia myrsinites

Orange hawkweed
Hieracium aurantiacum

Parrotfeather

Myriophyllum aquaticum

Purple loosestrife
Lythrum salicaria

Rush skeletonweed
Chondrilla juncea

Squarrose knapweed
Centaurea virgata

Tansy ragwort
Senecio jacobaea

Yellow starthistle
Centaurea solstitialis
     

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

Corn chamomile

Anthemis arvensis

Cutleaf teasel

Dipsacus laciniatus

Dalmatian toadflax

Linaria dalmatica & genistifolia

Dame's rocket

Hesperis matronalis

Diffuse knapweed

Centaurea diffusa

Eurasian watermilfoil

Myriophyllum spicatum

Hoary cress

Cardaria 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
Chrysanthemum leucanthemum

Perennial pepperweed
Lepidium latifolium

Plumeless thistle
Carduus acanthoides

Russian knapweed
Acroptilon repens

Russian-olive
Elaeagnus angustifolia

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

Scentless chamomile
Matricaria perforata

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
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

Elytrigia repens

Redstem filaree

Erodium cicutarium

Velvetleaf

Abutilon theophrasti

Wild-proso millet

Panicum miliaceum

Watch List Species

Asian mustard
Asian mustard

Brassica tournefortii
Baby's breath
Baby's breath

Gypsophila paniculata
Spiney cocklebur
Bathurst burr /
Spiney cocklebur

Xanthium spinosum

Brazilian elodea

Egeria densa

Common bugloss

Anchusa officinalis

Common reed

Phragmites australis

Garlic mustard
Alliaria petiolata
Garden loosestrife
Garden loosestrife
Lysimachia vulgaris
Himalayan blackberry
Himalayan blackberry
Rubus armeniacus

Japanese blood grass/
Cogongrass

Imperata cylindrical

Meadow hawkweed
Hieracium caespitosum

Onionweed
Asphodelus fistulosus

Purple pampasgrass
Cortideria jubata

Scotch broom
Cytisus scoparius

Sericea lespedeza
Lespedeza cuneata

Swainsonpea
Sphaerophysa salsula

Syrian beancaper
Zygophyllum fabago

Water hyacinth
Eichhornia crassipes

Water lettuce
Pistia stratiotes

White bryony
Bryonia alba

Woolly distaff thistle
Carthamus lanatus

Yellow flag iris
Iris pseudacorus

Yellow floatingheart
Nymphoides peltata

Yellowtuft
Alyssum murale & A. corsicum