Rock tripe is the common name for various lichens of the genus Umbilicaria that grow on rocks. They are widely distributed, including on bare rock in Antarctica, and throughout northern parts of North America such as New England and the Rocky Mountains. They are edible when properly prepared; soaking extensively and boiling with changes of water removes the bitterness and purgative properties. They have been used as a famine food in extreme cases when other food sources were unavailable, as by early American northern explorers.
Flavoparmelia caperata, the common greenshield lichen, is a foliose lichen that grows on the bark of trees, and occasionally on rock.
Flavoparmelia baltimorensis, the rock greenshield lichen, is a medium to large foliose lichen with a yellow green upper thallus surface when dry; its lobes are rounded without pseudocyphellae; and the upper surface is covered with globose, pustule-like growths resembling isidia. The lower surface is black with a narrow brown zone at the margins.
Umbilicaria americana, commonly known as frosted rock tripe, is a foliose lichen of rock faces.
Umbilicaria mammulata, or smooth rock tripe, is a foliose lichen found on boulders and rock walls.
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 climates that can range from cold, dry mountains to wet, warm valleys. Lichens develop quite slowly with recorded growth rates of 0.01–27mm/year depending on the species. Their lifespan averages between 30 and 60 years.
Lichen morphology includes lichen growth forms used to group lichens by "vegetative" thallus types, and forms of "non-vegetative" reproductive parts. Some lichen thalli have the aspect of leaves ; others cover the substrate like a crust, others such as the genus Ramalina adopt shrubby forms, and there are gelatinous lichens such as the genus Collema.
Xanthoparmelia conspersa, commonly known as the peppered rock-shield, is a foliose lichen and the type species of genus Xanthoparmelia. It is widely distributed in temperate zones, and has been recorded from Japan, Europe, Africa, North America, and South America.
Umbilicaria phaea is a brown, umbilicate foliose lichen that grows up to 6 cm (2.4 in) in diameter, sometimes in colonies covering large patches of desert rocks. One variety that grows in northern California is brilliant red. It is (monophyllous) with a single 1 – 5 cm flattish leaf-like cap on top of an anchoring stem (umbilicate). The leaflike top is smooth with some lobes, roughly circular, thin, and brittle. The lower surface is light gray to light brown. It has up to 2.5 mm black circular to slightly polygonal spots that are the fruiting bodies (apothecia), slightly sunken into the main nonfruiting body part (thallus). It grows on siliceous boulders in very dry climates of western North and South America, where it is usually the most common member of its genus.
Physcia caesia, known colloquially as blue-gray rosette lichen and powder-back lichen, is a species of foliose lichenized fungus. First described by Georg Franz Hoffmann in 1784, it is common across much of Europe, North America and New Zealand, and more patchily distributed in South America, Asia, Australia and Antarctica. There are 2 subspecies: P. c. caesia and P. c. ventosa, as well as a number of distinct forms and varieties. Molecular studies suggest that the species as currently defined may be polyphyletic. It is typically pale gray shading to darker gray in the center, and grows in a small rosette, usually some 2–3 cm (0.79–1.18 in) across at maturity. It only rarely has apothecia, instead reproducing most often vegetatively via soredia, which are piled in round blue-gray mounds across the thallus's upper surface. It grows most often on rock—principally calcareous, but also basaltic and siliceous—and also occurs on bone, bark and soil. It is nitrophilic and is particularly common on substrates where birds perch.
Peltigera canina, commonly known as the dog lichen, is a widely distributed species of foliose lichen in the family Peltigeraceae. It was originally described by Carl Linnaeus in his 1753 work Species Plantarum. German botanist Carl Ludwig Willdenow transferred it to the genus Peltigera in 1787. This species is currently undergoing research as it is likely multiple species under one united name.
Hypogymnia physodes, commonly known as the monk's-hood lichen, is a species of foliose lichen in the family Parmeliaceae. It is a common and widespread species in boreal and temperate forests of the Northern Hemisphere. It has a grey to yellowish-green thallus that is loosely attached to its substrate and forms large irregular patches. Hollow lobes are 2–3mm wide. The outer edge turns up and is frequently covered with white powdery soredia underneath. Its lower surface is black, wrinkled and has some browning toward the lobe margins. The pycnidia are black and abundant, and their presence creates a pepper-like effect across the upper surface. Because of its abundance and its moderate sensitivity to sulphur dioxide and heavy metals, Hypogymnia physodes is often used in bioindicator and biomonitoring studies that enable the assessment of air pollution and other environmental conditions.
Peltigera lepidophora, commonly known as the scaly pelt, is a species of foliose lichen in the family Peltigeraceae. It was first described by Finnish lichenologist Edvard August Vainio in 1878 as a variety of Peltigera canina. German botanist Friedrich August Georg Bitter promoted it to species status in 1904.
Peltigera lepidophora, commonly known as the fan lichen, is a species of foliose lichen in the family Peltigeraceae. It was first described by Carl Linnaeus in his 1753 work Species Plantarum as Lichen venosus. German botanist Georg Franz Hoffmann transferred it to the genus Peltigera in 1789. P. venosa can be found in temperate and boreal regions of North America, Europe, and Asia, while occasionally being found in drier climates such as mountainous Arizona.
Umbilicaria polyphylla, commonly known as petaled rock tripe, is a widely distributed species of saxicolous lichen in the family Umbilicariaceae. It was first described by Carl Linnaeus in his 1753 work Species Plantarum as Lichen polyphyllus. German botanist Johann Christian Gottlob Baumgarten transferred it to the genus Umbilicaria in 1790. The lichen has a dark brown to black thallus that measures 2–6 cm (0.8–2.4 in) in diameter. The upper surface is smooth, while the lower surface is sooty black. It grows on exposed rocks, typically in arctic-alpine habitats.
Umbilicaria hyperborea, commonly known as blistered rock tripe, is a species of foliose lichen in the family Umbilicariaceae. It is widely distributed in arctic and alpine regions.
Punctelia graminicola is a species of foliose (leafy) lichen in the family Parmeliaceae. It grows on rocks, and, less frequently, on bark in North America, South America, and East Africa. It has a blue-grey thallus measuring up to about 15 cm (6 in), covered with tiny pores called pseudocyphellae. Sometimes the lichen forms small lobes that project out from the surface. Fruiting bodies are uncommon in this species; if present, they resemble small cups with a brown internal disc measuring 3–10 mm (0.1–0.4 in) in diameter. A lookalike species, Punctelia hypoleucites, is not readily distinguishable from Punctelia graminicola by appearance or habitat alone; these species can only be reliably differentiated by examining the length of their conidia.
Cetrelia chicitae is a species of foliose lichen in the family Parmeliaceae. It is found in eastern Asia, North America, and Europe, where it grows on mossy rocks and tree trunks.
Umbilicaria virginis, commonly known as the blushing rock tripe, is a species of saxicolous (rock-dwelling) umbilicate lichen in the family Umbilicariaceae. It occurs in polar and alpine regions.
Umbilicaria maculata is a species of saxicolous (rock-dwelling) umbilicate lichen in the family Umbilicariaceae. It is found in high-altitude alpine locations in Poland and France.
