Leptogium apalachense Nyl.
A Species of Lichen
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Basis for Listing
The North American distribution of Leptogium apalachense is limited to the Appalachian region, the Ozarks, and one population in Minnesota. This species is apparently rare everywhere within this range. In Minnesota, it is known from a Blue Earth County collection in 1899, but it has not been found since. The expansion of the Mankato urban area probably eliminated the original population, although it may still survive at other locations along the Minnesota River. Leptogium apalachense was listed as an endangered species in Minnesota in 1984.
Leptogium apalachense is a foliose (leaflike) lichen. Its thallus (lichen body) is olive to brownish-gray, with long, narrow, radiating lobes, each less than 1 mm (0.04 in.) wide and 4-10 mm (0.16-0.39 in.) long. The lobes are dichotomously branched with fine wrinkles on the upper surface. Sometimes they are laterally recurved. The upper surface has apothecia (disk-shaped fruiting bodies) immersed in it, while isidia (fingerlike projections) and soredia (powdery reproductive structures) are absent. The lower surface of L. apalachense is bare or has very few rhizines (rootlike structures). Spores are submuriform (having both vertical and horizontal cross-walls), 14-25 µm long and 6-15 µm wide (Wetmore 1981). A similar lichen is L. plicatile, but it has flat lobes and isidia whereas L. apalachense has recurved lobes and no isidia.
Leptogium apalachense grows on shaded, moist, limestone cliffs. These habitats are rare in Minnesota. The species is found in similar habitats in other parts of its range, where it is always rare.
Biology / Life History
Reproducing sexually, the spores for this lichen are distributed by wind, water, animals, or insects. If spores land in a suitable environment, they must also associate with the appropriate algae to successfully form a new lichen thallus.
Conservation / Management
Habitat loss is a primary threat for this lichen. Contributing factors may include urban sprawl and the associated pollution, as well as quarry operations. Rock-climbing is probably not a threat because limestone is a suboptimal climbing surface. Given L. apalachense's preference for shaded, moist cliffs, climate change associated with global warming may alter the habitat enough to negatively affect any populations remaining in Minnesota.
Conservation Efforts in Minnesota
Scientists are searching for this and other rare lichens in an attempt to identify and possibly preserve local populations.
References and Additional Information
Sierk, H. A. 1964. The genus Leptogium in North America north of Mexico. The Bryologist 67:245-317.
Wetmore, C. M. 1981 (revised 2005). Keys to the Lichens of Minnesota. Department of Plant Biology, University of Minnesota, St. Paul, Minnesota. 92 pp.