Plant of the Week
Range map of Polemonium confertum. States are colored green where the species may be found.
Rocky Mountain Jacob's-ladder. Photo by Andrew Kratz, USDA Forest Service.
A closer view of the Rocky Mountain Jacob's-ladder flowers. Photo by Andrew Kratz, USDA Forest Service.
Alpine talus slope habitat. Photo by Andrew Kratz, USDA Forest Service.
Rocky Mountain Jacob's-ladder (Polemonium confertum)
By Andrew Kratz, USDA Forest Service
There are over 20 native species of Polemonium in the United States, many of which are called Jacob’s-ladder or sky pilot. Some species are widespread, occurring in many states, while others are confined within a single state. Rocky Moutain Jacob’s-ladder occurs only in central and southwestern Colorado, though it is not considered rare. Where its range overlaps that of Polemonium brandegeei, the two can cross to form hybrids.
This spectacular Jacob’s-ladder is found in the alpine, generally above 11,000 feet. It thrives in the harsh and rugged environment of scree slopes and talus. The plants can grow up to about a foot in height, and on a robust plant, the cluster of blue flowers is approximately the size of a tennis ball. Most people consider the flowers and foliage to have a somewhat unpleasant smell, but the species is available commercially for the home gardener.
Pollinators include bumblebees (Bombus rufocinctus) and Mason bees (Osmia species).