''Umbilicaria mammulata'', or smooth rock tripe, is a

foliose lichen Foliose lichen is one of the morphological classes of lichens, which are complex organisms that arise from the symbiotic relationship between fungi and a photosynthetic partner, typically algae. This partnership allows lichen to live in diverse ...

found on boulders and rock walls.

Description

''Umbilicaria mammulata'' is among the largest lichens in the world. The

thallus Thallus (plural: thalli), from Latinized Greek (), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria. Many of these organisms wer ...

of ''U. mammulata'' is usually in diameter, but specimens have been known to reach in the Smoky Mountains of

Tennessee Tennessee ( , ), officially the State of Tennessee, is a landlocked state in the Southeastern region of the United States. Tennessee is the 36th-largest by area and the 15th-most populous of the 50 states. It is bordered by Kentucky to th ...

. The smooth upper surface is a reddish-brown to grayish-brown color and the lower surface is pitch black.

Ecology

This species is found on boulders and steep rock walls in forests and around lakes. It grows on several types of rock substrate, such as

acidic rock Acidic rock or acid rock refers to the chemical composition of igneous rocks that has 63% wt% SiO2 content. Rocks described as acidic usually contain more than 20% of free quartz. Typical acidic rocks are granite or rhyolite. Term is used in che ...

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical form ...

, and

granitic rock A granitoid is a generic term for a diverse category of coarse-grained igneous rocks that consist predominantly of quartz, plagioclase, and alkali feldspar. Granitoids range from plagioclase-rich tonalites to alkali-rich syenites and from quartz- ...

.Wisconsin State Herbarium, "Wisconsin Vascular Plants: Details Page." http://www.botany.wisc.edu/Wislichens/scripts/detail.asp?SpCode=UMBMAM (accessed Dec 19, 2008). Like most lichens, ''U. mammulata'' is sensitive to air and water quality. If conditions are optimal, seeing rocks or cliffs covered in dinner plate-sized thalli is not unusual. However, it has been suggested that ''U. mammulata'' is not as sensitive to pH and water quality as it is to the frequency and duration of precipitation.

Gallery

Image:Umbilicaria mammulata 01.JPG, ''U. mammulata'' growing on a rock on Pratt Mountain. Image:Umbilicaria_mammulata-4.jpg, The smooth upper surface of ''U. mammulata''. Image:Umbilicaria_mammulata-3.jpg, The black bottom surface of ''U. mammulata''. Image:umbilicaria_mammulata _rt.jpg, ''U. mammulata'' on sandstone blocks in

Otter Creek Wilderness The Otter Creek Wilderness is a U.S. Wilderness area located in the Cheat-Potomac Ranger District of Monongahela National Forest in West Virginia, USA. The Wilderness sits in a bowl-shaped valley formed by Otter Creek, between McGowan Mountain and ...

, West Virginia.

References

mammulata Lichen species Lichens described in 1814 Lichens of Europe Lichens of North America Taxa named by Erik Acharius {{Lecanoromycetes-stub