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 IOSAndroid


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

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

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

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 maculosa

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

Flowering rush

Butomus umbellatus

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

Parrotfeather

Myriophyllum aquaticum

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