Weed List2017-08-10T22:58:29+00:00

The Colorado Noxious Weed Act and supporting Rules establish a prioritized list of noxious weeds. For detailed information visit the State’s site.

A List

List A species are invasive weeds that are either not known to occur in Colorado or are of very limited distribution and are required to be eradicated (completely eliminated).

African rue (Peganum harmala)
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 reed (Arundo donax)
Giant salvinia (Salvinia molesta)
Hairy willow-herb (Epilobium hirsutum)
Hydrilla (Hydrilla verticillata)
Japaneese, Giant and Bohemian knotweed (Polygonum cuspidatum, P. sachalinense and P.x bohemicum)
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)

B List

List B species are invasive weeds with populations of varying distribution and densities within the state. The level of mandated control is based on local conditions. These weeds may require eradication within certain areas of the state.

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, broad-leaved (Linaria dalmatica)
Dalmatian toadflax, narrow-leaved (Linaria 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 (Leucanthemum vulgare)
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 (Tripleurospermum perforatum)
Scotch thistle (Onopordum acanthium)
Scotch thistle (Onopordum tauricum)
Spotted knapweed (Centaurea maculosa)
Sulfur cinquefoil (Potentilla recta)
Wild caraway (Carum carvi)
Yellow nutsedge (Cyperus esculentus)
Yellow toadflax (Linaria vulgaris)

C List

List C species are widespread and common within the state. They may pose a risk to agricultural lands and may be required to be controlled.

Bulbous bluegrass (Poa bulbosa)
Chicory (Cichorium intybus)
Common burdock (Arctium minus)
Common mullein (Verbascum thapsus)
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 (Elymus repens)
Redstem filaree (Erodium cicutarium)
Velvetleaf (Abutilon theophrasti)
Wild proso millet (Panicum miliaceum)