Acer republicense is known from a single specimen which was recovered from an outcrop of the early Eocene, Ypresian[2] Klondike Mountain Formation in Republic. The section Stewarta contains only the species A. republicense.[1][2] The Klondike Mountain Formation preserves an upland temperate flora which was first interpreted as being microthermal,[1] however further study has shown the flora to be more mesothermal in nature.[2] The plant community preserved in the Klondike Mountain formation is a mixed conifer–broadleaf forest with large pollen elements of birch and golden larch, but also having notable traces of fir, spruce, cypress, and palm. A. republicense is one of a number of Acer species described from the Republic site by Wolfe and Tanai.[1] Like the associated species such as A. hillsi, A. spitzi, A. stonebergae and A. toradense, Acer republicense is only known from the samara fossils. This contrasts the species A. washingtonense and A. wehri which are known from both fossil samaras and leaves.[1]
The species was described from a solitary part and counterpart type specimen, the holotype samara, number UAPC S5414A, B, which is currently preserved in the paleobotanical collections of the University of Alberta in Edmonton, Alberta.[1] The specimen was studied by paleobotanists Jack A. Wolfe of the United States Geological Survey, Denver office and Toshimasa Tanai of Hokkaido University. Wolfe and Tanai published their 1987 type description for A. republicense in the Journal of the Faculty of Science, Hokkaido University.[1] The etymology of the chosen specific name republicense is in recognition of the type locality in Republic, Washington, and as the only species in the section Republica, the section name is a derivation of republicense.[1]
