On 14 July 2009, we visited Glenwood Canyon near Glenwood Springs, Colorado. The preserve is located in the montane life zone and includes forest that has a remarkably eastern feel to it, with many genera and species of plants that were very recognizable to this Indiana botanist. The steep cliffs and canyon walls quickly bring you back to the reality that you're definitely not in the Midwest.
Hanging Lake is the primary attraction at this location. As the name implies, Hanging Lake is positioned on the side of a canyon. The lake has formed after thousands of years of limestone precipitating from calcareous waters that are flowing down the mountain and over rocks and logs. The resulting travertine layers eventually formed a bowl-like feature that now cradles the clearest water I've ever seen.
Along our ascent as we approached the lake, we continually encountered a comely columbine (Aquilegia) with pink sepals and yellow petal blades that didn't match the columbines in any of the reference guides we had with us. We took numerous photographs thinking that we would need to see all aspects of this species to be able to property identify it later that evening.
Fortunately, we didn't have to wait that long. When we arrived at the lake itself, we encountered an informational sign identifying this curious columbine as Barneby's Columbine (Aquilegia barnebyi), a plant only known from two locations in the world - Hanging Lake and in Rio Blanco County in northwestern Colorado. We had no idea that this species, so abundant at this location, would have been so rare overall. At Glenwood Canyon, we saw Oil Shale Columbine, as it is also known, in forest, around Hanging Lake, and in a boggy seep (shown below).
Oil Shale Columbine is now also known from Utah, but is still considered endemic to the Green River drainage; it grows on cliff walls and on moist, calcareous soils (Whittemore 1997).
Whittemore, A.T. (1997). Aquilegia. In: Flora of North America Editorial Committee, eds. 1993+. Flora of North America North of Mexico. 15+ vols. New York and Oxford. Vol. 3.