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


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/
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