Polemonium, commonly called Jacob's ladders or Jacob's-ladders (the name derived from the Biblical story), is a genus of between 25 and 40 species of flowering plants in the family Polemoniaceae, native to cool temperate to arctic regions of the Northern Hemisphere. One species, Polemonium micranthum, also occurs in the southern Andes in South America. Many of the species grow at high altitudes, in mountainous areas. Most of the uncertainty in the number of species relates to those in Eurasia, many of which have been synonymized with Polemonium caeruleum.
Polemonium are perennial plants (rarely annual plants) growing 10–120 cm tall with bright green leaves divided into lance-shaped leaflets. They produce blue (rarely white or pink) flowers in the spring and summer.
Some species are used as food plants by the larvae of some Lepidoptera species including Coleophora polemoniella.
Species
Kew's Plants of the World Online accepts 37 species. Many are locally known simply as "Jacob's ladder".
Polemonium acutiflorum – tall Jacob's ladder Polemonium boreale – northern Jacob's ladder Polemonium brandegeei – Brandegee's Jacob's ladder Polemonium caeruleum – Jacob's ladder (the original plant to bear this name); charity Polemonium californicum – showy Jacob's ladder Polemonium campanulatum Polemonium carneum – royal Jacob's ladder Polemonium caucasicum Polemonium chartaceum – Mason's Jacob's ladder Polemonium chinense Polemonium confertum – Rocky Mountain Jacob's ladder Polemonium eddyense – Mount Eddy Jacob's-ladder Polemonium elegans – elegant Jacob's ladder Polemonium elusum – elusive Jacob's-ladder Polemonium eximium – sky pilot Polemonium foliosissimum – towering Jacob's ladder Polemonium glabrum Polemonium grandiflorum Polemonium hingganicum Polemonium kiushianum Polemonium majus Polemonium mexicanum Polemonium micranthum – annual polemonium Polemonium nevadense – Nevada Jacob's ladder Polemonium occidentale – western Jacob's ladder Polemonium pauciflorum – few-flower Jacob's ladder Polemonium pectinatum – Washington Jacob's ladder Polemonium pulchellum Polemonium pulcherrimum – beautiful Jacob's ladder Polemonium reptans – Jacob's ladder, Greek valerian Polemonium sachalinense Polemonium schizanthum Polemonium schmidtii Polemonium × speciosum Polemonium sumushanense Polemonium vanbruntiae – Vanbrunt's Jacob's ladder Polemonium × victoris Polemonium vilosissimum Polemonium villosum Polemonium viscosum – sticky polemonium Polemonium yezoense
References