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Oakmoss Lichen (Evernia prunastri)

Life history

Species overview

Oakmoss Lichen (Evernia prunastri), a Wisconsin Special Concern lichen, is found on conifer twigs in northern Wisconsin. Outside of Wisconsin it is more commonly found on deciduous trees and shrubs.

Synonyms: Borrera prunastri, Evernia herinii, Evernia prunastri f. herinii, Evernia prunastri f. retusa, Evernia prunastri var. herinii, Evernia prunastri var. prunastri, Evernia prunastri var. stictoceros, Evernia retusa, Evernia stictoceros, Lichen prunastri, Lichen stictoceros, Lobaria prunastri, Parmelia prunastri, Parmelia prunastri var. prunastri, Parmelia prunastri var. retusa, Physcia prunastri, Physcia prunastri f. elongata, Physcia prunastri f. prunastri, Platysma prunastri, Ramalina prunastri


  • Distinguishing characteristics: Oakmoss lichen can be distinguished from similar species by its branches, which are flat (vs. angular) and the color of its lower thallus surface, which is obviously paler than the upper surface.
  • Fruiting body characteristics: Apothecia are rare but, if present, occur marginally; disc red-brown.
  • Thallus (vegetative body) characteristics: Thallus tufted or pendant, green, yellow or greyish above and blue-grey below; shallow ridges visibly crisscross both thallus surfaces; branches linear and flattened.


  • Growth form: Fruticose lichen
  • Vegetative reproduction: Soralia on branch margins and upper thallus surface.
  • Comments: Associates: Balsam fir (Abies balsamea), red pine (Pinus resinosa), and spruce (Picea spp.). This species is used in the perfume and cosmetics industry in Europe but is not common enough here to support those uses.

General overview of lichen morphology

Lichens represent a unique symbiotic relationship between two or sometimes three organisms: a fungus; an alga; and/or a cyanobacterium. This figure provides a good overview of a generalized lichen. The main body of the lichen is called the thallus. The thallus is the vegetative part of the lichen (i.e., not including any reproductive structures like apothecia) and is often what we visually associate with a lichen. The figure above depicts a foliose thallus with the upper surface curled up in places to reveal the lower thallus surface. The magnified thallus cross section on the right shows a number of additional layers. In this example, the top layer is the upper cortex, which is made up of fungal filaments. Underneath that is the photobiont, either an alga or a cyanobacterium or both. Beneath the photobiont is a loose layer of fungal strands (hyphae) called the medulla, and below the medulla is the lower cortex.

Lichens can reproduce sexually via spores, which are associated with the fungal component of the lichen. However, these spores must again find an appropriate photobiont before a new lichen is formed. Lichens can also reproduce asexually. The two structures shown in the box on the left function in asexual reproduction. Both isidia and soredia are essentially photobionts wrapped in a fungal skin. These can be released from the thallus to form new lichens.

Please see the glossary below for descriptions of more lichen-related terms and photos that depict these features.

Glossary of common lichen terms [PDF]

State status

Status and Natural Heritage Inventory documented occurrences in Wisconsin

The table below provides information about the protected status - state and federal - and the rank (S and G Ranks) for Oakmoss Lichen (Evernia prunastri). See the Working List Key for more information about abbreviations. Counties shaded blue have documented occurrences for this species in the Wisconsin Natural Heritage Inventory database. The map is provided as a general reference of where this species has been found to date and is not meant as a range map.

Documented locations of Evernia prunastri in the Natural Heritage Inventory Database as of July 2015.

Summary Information
State StatusSC
Federal Status in Wisconsinnone
State RankS1
Global RankG5
Mapped in NHIY

Habitats and landscapes

The Natural Heritage Inventory has developed scores indicating the degree to which certain rare lichen species are associated with a particular natural community or ecological landscape. This information is similar to that found in the Wildlife Action Plan for animals. As this is a work in progress, we welcome your suggestions and feedback.

General habitat information

Found on conifer twigs in northern Wisconsin. Outside of Wisconsin it is more commonly found on deciduous trees and shrubs.

Natural communities

This table lists the natural communities that are associated with Oakmoss Lichen. Scores for natural community associations are: "significant" association (score=3), "moderate association" (score=2) or the species can be present but is only weakly associated with the community (score=1).

Natural communities score

Ecological landscapes

This table lists the ecological landscape association scores for Oakmoss Lichen. The scores (3=High, 2=Moderate, 1=Low, 0=None) also correspond to the map.

Ecological landscape score

Species guidance

The Endangered Resources Program has developed avoidance measures and management guidelines for lichens on the Natural Heritage Working List. These are a work in progress, and we welcome your suggestions and feedback.

Avoidance measures

These are specific actions designed to avoid "take" (mortality) of this species.

  • No avoidance measures have been developed for this species.

Management guidance

Management guidelines are additional considerations that may help maintain or enhance habitat for this species

  • No guidance has been developed for this species.


Oakmoss Lichen  Photo.

The thallus branches of oakmoss lichen are flat, compared to the more angular branches of similar-looking lichens.

Photo © Einar Timdal.

Oakmoss Lichen  Photo.

The soralia occur in this photo on the branch tips and margins.

Photo © Einar Timdal.

Support for Wisconsin's rare lichen information has been provided by the Wisconsin Rare Plant Preservation Fund. To donate, visit the Natural Resources Foundation of Wisconsin [exit DNR].

Last revised: Thursday, October 08, 2020
Southwest Savanna Southern Lake Michigan Coastal Western Coulees and Ridges Southeast Glacial Plains Central Sand Hills Central Lake Michigan Coastal Central Sand Plains Northern Lake Michigan Coastal Northern Lake Michigan Coastal Northeast Sands Western Prairie North Central Forest Northern Highlands Northwest Lowlands Northwest Sands Northwest Lowlands Superior Coastal Plains Forest Transition