Beckwithia is a small genus of flowering plants in the buttercup family Ranunculaceae, placed within the order Ranunculales. The genus is taxonomically controversial: most botanists treat it as synonymous with a clade containing the glacier buttercup (Ranunculus glacialis) and Anderson's buttercup (Ranunculus andersonii), and molecular studies have further supported the placement of B. glacialis and B. camissonis within Ranunculus, genetically distant from B. andersonii.
The genus comprises a small number of taxa — buttercup-like perennial herbs adapted to extreme environments. Beckwithia glacialis (the glacier buttercup) is among the hardiest flowering plants on Earth, growing at high elevations and in boreal and arctic regions of Europe, including Iceland, Jan Mayen, and Svalbard, as well as populations in Alaska and Siberia. Beckwithia andersonii (Anderson's buttercup) is native to the western United States. Due to the contested circumscription of the genus, species are often treated under Ranunculus in modern flora treatments, though Beckwithia remains a recognized name in some classifications.
Distribution
Beckwithia taxa are distributed across arctic, boreal, and alpine zones of the Northern Hemisphere. B. andersonii (Anderson's buttercup) is native to the western United States. B. glacialis subsp. glacialis (the glacier buttercup) occurs in alpine and boreal Europe, including Iceland, Jan Mayen, and Svalbard. B. glacialis subsp. alaskensis is endemic to the Kigluaik Mountains of the Seward Peninsula, Alaska. B. camissonis occurs on both sides of the Bering Strait, in Siberia and Alaska.
Taxonomy Notes
Beckwithia's status as a distinct genus is disputed. Most botanists consider it synonymous with part of Ranunculus, and molecular studies have shown that B. glacialis and B. camissonis are embedded within Ranunculus, while B. andersonii is phylogenetically distant from them. The genus name was published by Jepson, and species epithets carry authorities including A. Gray, L., Á. Löve & D. Löve, Jurtz., D. Murray & S. Kelso, Schltdl., and Tolm.
