Colorado butterfly plant occurs on soils derived from conglomerates, sandstones and tuffaceous mudstones and siltstones of the Tertiary White River, Arikaree and Oglalla formations (Love and Christiansen 1985) on level or slightly sloping floodplains and drainage bottoms at elevations of 4,850 to 6,400 feet. Populations are typically found in habitats created and maintained by streams active within their floodplains, with vegetation that is relatively open and not overly dense or overgrown (65 FR 62302; October 18, 2000). Populations are often found in a variety of ecological settings, including low depressions or along bends in wide, active, meandering stream channels slightly upslope of the channel, though at least one population also occurs in a spring-fed wet meadow.

Typically, Colorado butterfly plant habitat is open, without dense or woody vegetation. The establishment and survival of seedlings appears to be enhanced at sites where tall and dense vegetation has been removed by some form of disturbance. In the absence of occasional disturbance, the plant’s habitat can become choked by dense growth of willows, grasses and exotic plants. This prevents new seedlings from becoming established and replacing plants that have died (Floyd 1995a; Fertig 1996). 

It commonly occurs in communities dominated by non-native and disturbance-tolerant native species including Agrostis stolonifera (creeping bentgrass), Poa pratensis (Kentucky bluegrass), Glycyrrhiza lepidota (American licorice), Cirsium flodmanii (Flodman’s thistle), Grindelia squarrosa (curlytop gumweed), and Equisetum laevigatum (smooth scouring rush). Its habitat on Warren AFB includes wet meadow zones dominated by Panicum virgatum (switchgrass), Muhlenbergia richarsonis (mat muhly), Schizachyrium scoparium (little bluestem) and other native grasses. All of these habitat types are usually intermediate in moisture ranging from wet, streamside communities dominated by sedges, rushes and cattails to dry, upland prairie habitat. In areas of suitable habitat for Colorado butterfly plant, Salix exigua (coyote willow), Cirsium arvense (Canada thistle), and Euphorbia esula (leafy spurge) may become dominant; the willow in particular increases in the absence of grazing or mowing. These species can outcompete and displace Colorado butterfly plant, presumably until another disturbance removes competing vegetation and creates openings for Colorado butterfly plant seedlings to germinate.

The final designation of critical habitat (70 FR 1940, January 11, 2005) for Colorado butterfly plant included the following critical habitat primary constituent elements:

1. Subirrigated, alluvial soils on level or low-gradient floodplains and drainage bottoms at elevations of 1,524 to 1,951 meters (5,000 to 6,400 feet);
2. A mesic moisture regime, intermediate in moisture between wet and dry, streamside communities dominated by sedges, rushes, cattails and dry upland shortgrass prairie;
3. Early- to mid-succession riparian riparian
   Definition of riparian habitat or riparian areas.
   
   Learn more about riparian (streambank or riverbank) plant communities that are open and without dense or overgrown vegetation (including hayed fields that are disced every 5 to 10 years at a depth of 8 to 12 inches, grazed pasture, other agricultural lands that are not plowed or disced regularly, areas that have been restored after past aggregate extraction, areas supporting recreation trails and urban/wildland interfaces); and
4. Hydrological and geological conditions that maintain stream channels, floodplains, floodplain benches and wet meadows that support patterns of plant communities associated with Colorado butterfly plant.

First-year plants consist of a ground-level basal rosette of oblong, 1- to 7-inch-long, hairless leaves clustered at ground level that persists for one to several years. In the flowering stage, this plant has one to a few reddish, hairy stems that are 2 to 4 feet tall with sparse small leaves. Flowers are arranged in a branched elongate inflorescence above the leaves. Flowers are located below the rounded buds and above the mature fruits. Individual flowers are 5 to 14 millimeters (0.25 to 0.5 inch) long with four reddish sepals and four white petals that turn pink or red with age. The hard, nut-like fruits are four-angled capsules and have no stalk (Marriott 1987; Fertig 1994; Fertig et al. 1994; Fertig 2000b, Heidel et al. 2008).

The Colorado butterfly plant is a short-lived perennial monocarpic or semelparous herb. Seeds of the Colorado butterfly plant germinate in spring and produce single basal rosettes that persist for one to a few years. After a rosette has reached sufficient above- and/or below-ground resources, the plant grows one to several central stems which flower and produce fruit once and then the plant dies. In the flowering stage, flowers sequentially open up the stem so that only a few flowers are open on any stem at a given point in time (Marriott 1987; Fertig 1994; Fertig et al. 1994; Fertig 2000a, 2000b, 2001).

Pollinators for related species of Gaura and Colyphus (Onagraceae, tribe Onagreae) consist of noctuid moths (Noctuidae) and halictid bees (Lasioglossum; Clinebell et al. 2004), and both moths and bees have been identified visiting Colorado butterfly plant flowers during annual censusing (USFWS 2016). Additionally, one study found that Colorado butterfly plant does not exhibit a bimodal pollination system that is seen in other Gaura species since the majority of pollination occurs at night by noctuid moths (Krakos et al. 2013).

Research on reproductive ecology of this species found that Colorado butterfly plant is self-compatible, but does not appear to be pollen-limited, meaning pollination events do not fertilize all ovules (Krakos et al. 2014, p. 528). Self-compatibility has been suggested as a mechanism to overcome pollen limitation in other related species (Krakos et al. 2014, p. 523). The hard, four-angle nut-like fruits produced from each flower contain three to five seeds (Burgess et al. 2005). There are no apparent adaptations for dispersal; many seeds fall to the ground around parent plants (Floyd and Ranker 1998), and, because the seed floats, others may be dispersed downstream. Livestock and native ungulates could provide an important dispersal mechanism as well through ingestion of the seeds (USFWS 2012, p. 27). We are unsure how long seeds persist in the soil, though a population presumed extirpated by dewatering in Nebraska was rediscovered during an occasional monitoring event over 10 years later after water was reintroduced to the drainage (Wooten 2008). Additionally, seeds that were stored for five years in cold storage had more viable seeds per capsule than more recent seed collections at 16, four, three and two months (Burgess et al. 2005). This provides evidence of a seed bank, an adaptation that enables species to take advantage of favorable growing seasons, particularly in flood-prone areas (Holzel and Otte 2004).