Watch List

The Colorado Watch List pdf file consists of 22 species that have been determined to pose a potential threat to the agricultural productivity and environmental values of the lands of the state and require careful observation. Many species included on this list are not yet known to occur in the state but have been recognized as noxious or problematic by another state or states in the region. For the included species that do occur in Colorado, more information is needed about the distribution and effect on agricultural and natural lands in the state.

If you find a population of one of the Watch List species, please fill out the Spotter Form.


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
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


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/

Imperata cylindrical


Meadow hawkweed © Richard Old

Meadow hawkweed
Hieracium caespitosum


Onionweed © William Ciesla 

Asphodelus fistulosus


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

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
Nymphoides peltata


Alyssum murale & A. corsicum