Comptonia columbiana

Content sourced from Wikipedia, licensed under CC BY-SA 3.0.

Comptonia columbiana is an extinct species of sweet fern in the Myricaceae family. It is known from fossil leaves found in the early Eocene deposits of western North America—central to southern British Columbia and northern Washington—with possible finds from southern Idaho and Oregon dating to the late Eocene or earliest Oligocene.

The species was likely an understory plant in warm temperate forests of the Okanagan Highlands, a group of upland lake systems with a mild, wet climate. Fossils come from the Allenby and Tranquille Formations, and later discoveries include the Falkland flora, McAbee, Thomas Ranch, Quilchena, and Klondike Mountain Formation sites. Klondike Mountain fossils have ages around 49–51 million years ago.

Leaves of C. columbiana are simple, lobed, and double-toothed. Each lobe usually has two main veins and 1–3 teeth at the tip. Leaf sizes vary by site, with specimens ranging roughly from 2 to 8 centimeters long. Some Okanagan Highlands specimens show deeper lobes than later Oligocene leaves, which helps distinguish the fossil records.

Comptonia columbiana is important in plant history as the oldest clearly identified member of the Myricaceae. It has been used in evolutionary studies as a calibration point for dating the family. There is also evidence of insect leaf mining on a Klondike Mountain leaf, though Comptonia itself is not a host for living Heliozelidae moths. Some Bridge Creek fossils from Oregon have been variably assigned to this species in the past.