“Rock tripe”, genusUmbilicaria, is an edible lichen. There are 65 species of rock tripe, found in rocky or mountainous environments worldwide, especially where other organisms are scarce. The common rock tripe, scientific nameUmbilicaria mammulata, grows on shaded rocks in the forests of eastern North America. The genus name Umbilicaria refers to the lichen’s single attachment point in the middle, like a navel. The species name mammulata, literally means small breasted but is more accurately translated as bumpy, describing the papillae or bumps on the black lower side of the lichen. The common name in French is “tripe-de-roche”, the exact translation of the English. It was eaten as survival food by French Canadian settlers, and traditionally boiled in soups by the Cree and other Native Canadians.
UPPER SURFACE: 4-15(-30) cm, smooth, dull, grayish to brownish
LOWER SURFACE: black, covered with dense black rhizines
CHEMISTRY: medulla C+ and KC+ red
Common in eastern North America, is it elsewhere in the world, too? I know there is a similar species in Japan, U. esculenta (sold as iwatake in markets, though apparently hard to find nowadays according to Japanese friends).
Common Name: Rock Tripe
Large grayish to brownish (greenish when wet) umbilicate lichen with black densely rhizinate lower surface. Will cover shaded rocks in deciduous forests in eastern North America, looking like someone has pasted withered old gray/blackened orange peels all over the rock.
On boulders and cliffs in deciduous forests, or near lakeshores.
Nothing comes close.
If boiled sufficiently, apparently this becomes edible. I found it very reminiscent of shoe leather, personally. But it’s listed in wilderness survival handbooks all the time as a good source of protein.
U. mammulata is among the largest lichens in the world. The thallus of U. mammulata is usually 4 to 15 centimeters in diameter, but specimens have been known to reach 63-centimetre (2.07 ft) in the Smoky Mountains of Tennessee. The smooth upper surface is a reddish-brown to grayish-brown color and the lower surface is pitch black.
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 acid rock, sandstone, quartz, and granitic rock. 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.
U. mammulata growing on a rock on Pratt Mountain.
U. mammulata on sandstone blocks in Otter Creek Wilderness, West Virginia.