Polemonium occidentale is a species of flowering plant in the phlox family known by the common names western polemonium and western Jacob's-ladder. There are two subspecies.Schmidt, L. J. Conservation Assessment for Polemonium occidentale v. lacustre, Western Jacob's Ladder. USFS. September 2003. The common ssp. occidentale is native to western North America from British Columbia to Colorado to California, where it can be found in moist areas of many habitat types, including meadows and woodlands. There is also a rare subspecies, ssp. lacustre, which is known only from a total of three counties in Minnesota and Wisconsin, and is found only in white cedar swamp habitat there.
This is a rhizomatous perennial herb producing an erect stem up to one meter tall. The leaves are located along the stem, each divided into many small lance-shaped leaflets. The inflorescence is an open, elongated array of several bell-shaped, five-lobed flowers each up to 1.5 centimeters long. The flower corolla is blue to bright purple with a white throat.
Taxonomy Botanist Edward Lee Greene scientifically described Polemonium occidentale in 1890, placing it in the Polemonium genus. Along with its genus it is classified in the Polemoniaceae family. The rare species Polemonium lacustre was initially described as a subspecies of Polemonium occidentale, there are five populations that grow in swamps in Wisconsin and Minnesota.Center for Plant Conservation Although it has no accepted subspecies, it has one among its eleven synonyms and has also been described as a subspecies twice.
Table of Synonyms Name Year Rank Notes Polemonium acutiflorum subsp. occidentale 1948 subspecies ≡ hom. Polemonium caeruleum subsp. amygdalinum 1958 subspecies = het. Polemonium caeruleum var. foliosissimum 1870 variety = het. Polemonium caeruleum subsp. occidentale 1950 subspecies ≡ hom. Polemonium caeruleum var. occidentale 1956 variety ≡ hom. Polemonium caeruleum var. pterospermum 1845 variety = het. Polemonium helleri 1907 species = het. Polemonium intermedium 1913 species = het. Polemonium occidentale subsp. amygdalinum 1942 subspecies = het. Polemonium occidentale var. intermedium 1907 variety = het. Polemonium occidentale subsp. typicum 1942 subspecies ≡ hom., not validly publ. Notes: ≡ homotypic synonym; = heterotypic synonym
References
External links Jepson Manual Treatment: ssp. occidentale Photo gallery