''Polemonium foliosissimum'', the towering Jacob's-ladder, is a rare species of flowering plant in the phlox family

Polemoniaceae The Polemoniaceae (Jacob's-ladder or phlox family) are a family of flowering plants consisting of about 25 genera with 270–400 species of annuals and perennials native to the Northern Hemisphere and South America, with the center of diversity ...

, native to the western United States; Arizona, Colorado, Idaho, Nevada, New Mexico, Utah and Wyoming. As its synonym ''Polemonium archibaldiae'' it has gained the

Royal Horticultural Society The Royal Horticultural Society (RHS), founded in 1804 as the Horticultural Society of London, is the UK's leading gardening charity. The RHS promotes horticulture through its five gardens at Wisley (Surrey), Hyde Hall (Essex), Harlow Carr (Nort ...

Award of Garden Merit The Award of Garden Merit (AGM) is a long-established annual award for plants by the British Royal Horticultural Society (RHS). It is based on assessment of the plants' performance under UK growing conditions. History The Award of Garden Merit ...

Subtaxa

The following varieties are accepted: *''Polemonium foliosissimum'' var. ''alpinum'' Brand - Idaho, Nevada, Utah, Wyoming *''Polemonium foliosissimum'' var. ''foliosissimum'' - Arizona, Colorado, New Mexico, Utah

References

foliosissimum Endemic flora of the United States Flora of Arizona Flora of Colorado Flora of Idaho Flora of Nevada Flora of New Mexico Flora of Utah Flora of Wyoming Plants described in 1878 Flora without expected TNC conservation status {{Polemoniaceae-stub