Chestnut Wrinkle Lichen

Cetraria sepincola, the chestnut wrinkle-lichen, is a species of foliose lichen in the family Parmeliaceae. It forms compact, cushion-like colonies typically 0.5–2 cm high, with a yellowish-green to dark brown upper surface and lighter underside. The species has a primarily circumboreal distribution and is widespread in northern regions, occurring from Alaska to northern California in North America and documented as far south as Argentina.

While mainly found growing on woody species like Betula, Sorbus, Salix, and Alnus in bog environments and open areas, it can occasionally be found on dead wood and rarely on rock surfaces. Originally described by Jakob Friedrich Ehrhart in 1783 as Lichen sepincola, it was transferred to the genus Cetraria by Erik Acharius in 1803.

This epiphytic lichen grows primarily on the bark of deciduous and coniferous trees, as well as on wooden fences, posts, and other wooden substrates in open woodlands, forest edges, and semi-natural habitats. It requires specific humidity and air quality conditions typical of well-ventilated but sheltered environments.