WYOMING’S
 

Threatened and Endangered 

Plant Species
 

Colorado Butterfly Plant
	

Bureau of Land Management 

BLM
Leafy spurge (Euphorbia esula), 

Hound’s-tongue (Cynoglossum 

officinale), Canada thistle 

(Cirsium arvense), and 

Dalmatian toadflax (Linaria 

dalmatica). 

Colorado 

butterfly 

plant 

prefers open 

habitat that is 

not substantially 

overgrown by other 

vegetation, characteristic of 

areas that have been disturbed 

in recent years. As ecological 

Colorado Butterfly Plant 

Colorado butterfly plant (Gaura 

neomexicana ssp. coloradensis) is 

a striking plant of the North and 

South Platte River watersheds of 

southeastern Wyoming, western 

Nebraska, and northeastern 

Colorado. “Colorado” butterfly plant 

is a somewhat misleading name 

given that over twice as many 

populations are known from 

Wyoming than Colorado 

or Nebraska (the name 

commemorates the 

fact that subspecies 

coloradensis was only 

found in Colorado 

when it was first 

discovered in 1895). 

In Wyoming, it is 

known only from 

Laramie and Platte 

counties. The species was 

designated as threatened 

under the Endangered Species 

Act by the U.S. Fish and Wildlife 

Service on October 18, 2000. 

desCriPtion 

The Colorado butterfly plant is a 

member of the Evening primrose 

family (Onagraceae). Members 

of this family are distinguished 

by having flowers with four petals that are fused at the base into 

a slender tube situated above the 

seed-producing ovary. The flowers of Colorado butterfly plants 

are unlike most plants in being 

bilaterally symmetrical (having 2 

mirrored halves when divided in 

one plane) and shaped somewhat 

like the fore and hind wings of 

a butterfly. When flowers first 

open, the showy, 3/8 inch long 

petals are white but turn pink 

with age. The female portion of 

the plant, called a pistil, extends 

from the flower and contains a 

four-lobed “cross” at the tip on 

which pollen is deposited during pollination. The hard, diamond-shaped fruits are 4-angled 

in cross-section and attached 

directly to the stem. The Colorado butterfly plant is a shortlived perennial plant that 

typically lives from 2-6 

years. Typical plants 

are 11⁄2 to 2 feet tall 

with leaves over 

11⁄2 inches long and 

approximately 3/8 

inches wide. 

life History 

The Colorado 

butterfly plant 

flowers from late June 

until late September 

or October, depending on 

the date of the first hard frost. 

Like many other members of 

the Evening primrose family, 

Colorado butterfly plant flowers 

open at dusk and are lightcolored to attract nocturnal 

insect pollinators, such as moths. 

While the primary pollinators 

of Colorado butterfly plant 

have not yet been documented 

one possible candidate is the 

Clouded crimson moth (Schinia 

gaurae) which commonly feeds 

on members of the butterfly 

plant genus as a caterpillar. In 

controlled studies, the Colorado 

butterfly plant has been shown 

to be self-compatible (capable 

of self-pollination), but in 

nature it is thought to reproduce 

primarily by outcrossing and 

requires an insect pollinator for 

assistance. 

Fruits begin to mature in 

late July and continue to ripen 

through September. Individual 

fruits contain 1-4 seeds and a 

robust butterfly plant can produce 

as many as 383 fruits. Studies 

show that Colorado butterfly 

plant produces a seed bank, 

providing a reserve of 

seeds in the ground 

that can wait as 

many as five years 

for favorable 

environmental 

conditions before 

germinating. 

This gives 

the Colorado 

butterfly 

plant a means 

of survival 

during years 

of inhospitable 

conditions, and 

likely enables the 

plant to persist 

through severe 

environmental 

conditions such 

as prolonged 

drought. 

HaBitat 

The Colorado 

butterfly plant 

typically is found 

in wetland habitats 

along meandering 

stream channels on 

the high plains. In 

undisturbed sites, 

it grows among 

native grasses 

and forbs like 

switchgrass (Panicum 

virgatum), little 

bluestem (Schizachyrium 

scoparium), Flodman’s thistle 

(Cirsium flodmanii), and 

Canadian goldenrod (Solidago 

canadensis). The Colorado 

butterfly plant can also occur in 

wetland sites being invaded by 

non-natives, including Redtop 

(Agrostis stolonifera), Kentucky 

bluegrass (Poa pratensis), 

succession continues and 

more vegetation begins to take 

over its habitat, the Colorado 

butterfly plant tends to die 

out. Historically, flooding was 

probably the most important 

type of disturbance creating and 

maintaining open habitat. 

Wildfire and grazing also 

were historically present 

and likely were important 

in creating and maintaining 

Colorado butterfly plant habitat. 

Conservation 

The Endangered Species Act defines 

a threatened species as any species 

which is likely to become in danger 

of extinction within the foreseeable 

future throughout all or a significant 

portion of its range. Federal law 

prohibits the removal or destruction 

of threatened plants on any federal 

land or as a result of federal actions. 

As a federally-listed threatened 

species, the Colorado butterfly 

plant also receives protection under 

BLM’s Special Status Species 

management policy. 

In 2004, the U.S. Fish 

and Wildlife Service initiated 

habitat conservation agreements 

with private landowners on 

whose property the Colorado 

butterfly plant occurs. These 

conservation agreements provide 

specific measures to address 

potential threats due to herbicide 

application, livestock grazing, 

and hay production. Eleven such 

agreements are in place providing 

protection to over 2,500 acres of 

habitat along 37 miles of stream. 

An additional 3,500 acres, along 

approximately 51 miles of stream, 

has been designated as critical 

habitat under the Endangered 

Species Act. Annual monitoring 

conducted through conservation 

agreements, and research conducted 

by University of Wyoming and 

Wyoming Natural Diversity 

Database on F.E. Warren Air 

Force Base, is providing important 

scientific information on which 

long-term recovery ultimately 

depends. 
 

 

 

 

 

 

Suggested Reading 

Fertig, W. 2000. Status review of the Colorado 

butterfly plant (Gaura neomexicana ssp 

coloradensis). Wyoming Natural Diversity Database, 

Laramie, Wyo. 

Grunau, L., R. Schorr, and J. Handwerk. 2004. 

Conservation and management plan for Colorado 

butterfly plant and Preble’s meadow jumping mouse 

on F.E. Warren Air Force Base. Colorado Natural 

Heritage Program, Fort Collins, CO. for F.E. Warren 

Air Force Base. 

Heidel, B. 2008. 20-year population trends of a 

short-lived riparian species, Colorado butterfly 

plant (Gaura neomexicana ssp. coloradensis; 

Onagraceae), on F.E. Warren Air Force Base. 

Wyoming Natural Diversity Database, Laramie, 

Wyo. 

For more information contact: 

Bureau of Land Management 

(307) 775-6256 

U.S. Fish and Wildlife Service 

(307) 772-2374 

Wyoming Natural Diversity Database 

(307) 766-3020 

Citation: 

B. Heidel, W. Fertig, F. Blomquist, and T. 

Abbott. 2008. Wyoming’s Threatened and 

Endangered Species: Colorado Butterfly Plant. 

Wyoming Bureau of Land Management, 

Cheyenne, Wyo. In collaboration with 

Wyoming Natural Diversity Database. 

Note: New data on the biology and status of 

this species are being collected constantly, and 

parts of the information in this publication may 

become outdated. The fact sheet provides a 

general overview of the status of this species 

and is not intended as the sole source of 

species information for planning and research 

purposes. For additional information on this or 

other threatened and endangered species, or for 

additional copies of this publication, refer to the 

suggested readings or contact the botany contacts 

of the Bureau of Land Management in Wyoming, 

U.S. Fish and Wildlife Service in Wyoming, and 

the Wyoming Natural Diversity Database. 

This Colorado Butterfly Plant fact sheet is one in a 

series on Wyoming’s Threatened and Endangered 

Plant Species published by Bureau of Land 

Management and the Wyoming Natural Diversity 

Database. 

Front and back cover photo by B. Heidel 

Inset photo by T. Abbott 

Colorado butterfly plant illustration by B. Heidel 

BLM/WY/AE-09/007+1150