About Polemonium occidentale Greene
Polemonium occidentale, commonly known as western polemonium and western Jacob's-ladder, is a flowering plant species in the phlox family. This species has two recognized subspecies. The more common subspecies, Polemonium occidentale ssp. occidentale, is native to western North America, ranging from British Columbia through Colorado to California. It grows in moist areas across many habitat types, including meadows and woodlands. The second subspecies is the rare Polemonium occidentale ssp. lacustre, which is found only in three total counties in Minnesota and Wisconsin, and occurs exclusively in white cedar swamp habitat within this range. Polemonium occidentale is a rhizomatous perennial herb that grows an erect stem reaching up to one meter in height. Its leaves grow along the stem, and each leaf is divided into many small, lance-shaped leaflets. The inflorescence is an open, elongated cluster made up of several bell-shaped, five-lobed flowers. Each flower grows up to 1.5 centimeters long, and its corolla ranges from blue to bright purple with a white throat. The rare subspecies P. occidentale ssp. lacustre is threatened by several factors, including peat mining in its native swamp habitat, herbivory by deer, and changes to local hydrology at its growing sites. Only five populations of this rare subspecies are known to exist.
