Edible lichens are lichens that have a cultural history of use as a food. Although almost all lichen are edible (with some notable poisonous exceptions like the wolf lichen, powdered sunshine lichen, and the ground lichen [1] ), not all have a cultural history of usage as an edible lichen. [2] [3] Often lichens are merely famine foods eaten in times of dire needs, [4] but in some cultures lichens are a staple food or even a delicacy. Some lichens are a source of vitamin D. [5]
Although there are many lichen species throughout the world, only a few species of lichen are known to be both edible and provide any nutrition. [6] Two problems often encountered with eating lichens is that they usually contain mildly toxic secondary compounds, and that lichen polysaccharides are generally indigestible to humans. Many human cultures have discovered preparation techniques to overcome these problems. Lichens are often thoroughly washed, boiled, or soaked in ash water to help remove secondary compounds.
Recent analytics within the field have identified 15 kinds of edible lichen, [7] [ failed verification ] which have been mostly found in China. Due to its rubbery consistency, individuals within China fry, boil, and pressure-cook edible lichens. [8] [ failed verification ] Further, edible lichens can be made into beverages such as tea. [9]
In the past Iceland moss (Cetraria islandica) was an important human food in northern Europe and Scandinavia, and was cooked in many different ways, such as bread, porridge, pudding, soup, or salad. Bryoria fremontii was an important food in parts of North America, where it was usually pitcooked. It is even featured in a Secwepemc story. Reindeer lichen ( Cladonia spp.) is a staple food of reindeer and caribou in the Arctic. Northern peoples in North America and Siberia traditionally eat the partially digested lichen after they remove it from the rumen of caribou that have been killed. It is often called 'stomach icecream'. Rock tripe ( Umbilicaria spp. and Lasallia spp.) is a lichen that has frequently been used as an emergency food in North America.
One species of Umbilicaria, Iwa-take (U. esculenta), is used in a variety of traditional Korean and Japanese foods. It is quite expensive, and is collected off the sides of cliffs.
In India, The Middle East, and Niger, Parmotrema reticulatum （= Rimelia reticulata), Ramalina conduplicans, and Parmotrema tinctorum are used as spices and flavor enhancers. [10] Such substances are made through a process in which the edible lichens are dehydrated. [11] In India, Parmotrema perlatum lichen is a popular ingredient of many spice mixes, such as garam masala, kaala masala and goda masala, bhojwar masala from Hyderabad and potli masala of Uttar Pradesh. The lichen is usually described as lacking in specific flavors or aromas by cooks, but via various cooking techniques it contributes to a rich aromatic profile and umami taste of many dishes. [12]
Limbu and Rai people of northern Indian subcontinent consider several lichen species (with Hypotrachyna cirrhata (= Everniastrum cirrhatum), Hypotrachyna nepalensis（= Everniastrum nepalense), and Parmotrema cetratum being the preferred species) a delicacy and bulking agent. Ethnobotanists name the Limbu and Sherpa people as most lichenophilic in the region, compared to Brahmin, Chhetri and Tamang people. [13] Sargyangma, a kind of sausage made up of minced pork, pork intestines, pork fat, pork’s blood, eggs, lichen, rice and spices is a very popular Limbu dish. [14] [15]
Examples of edible lichen, grouped by their families, include:
A lichen is a symbiosis of algae or cyanobacteria living among filaments of multiple fungi species, along with a yeast embedded in the cortex or "skin", in a mutualistic relationship. Lichens are important actors in nutrient cycling and act as producers which many higher trophic feeders feed on, such as reindeer, gastropods, nematodes, mites, and springtails. Lichens have properties different from those of their component organisms. They come in many colors, sizes, and forms and are sometimes plant-like, but are not plants. They may have tiny, leafless branches (fruticose); flat leaf-like structures (foliose); grow crust-like, adhering tightly to a surface (substrate) like a thick coat of paint (crustose); have a powder-like appearance (leprose); or other growth forms.
A blood sausage is a sausage filled with blood that is cooked or dried and mixed with a filler until it is thick enough to solidify when cooled. Most commonly, the blood of pigs, sheep, lamb, cow, chicken, or goose is used.
Cladonia rangiferina, also known as reindeer cup lichen, reindeer lichen or grey reindeer lichen, is a light-colored fruticose, cup lichen species in the family Cladoniaceae. It grows in both hot and cold climates in well-drained, open environments. Found primarily in areas of alpine tundra, it is extremely cold-hardy.
The Limbu or Yakthung (endonym) are a Tibeto-Burman ethnolinguistic group indigenous to the Himalayan region of eastern Nepal, Sikkim, Assam, Nagaland, northern West Bengal, and western Bhutan.
Parmelia is a genus of medium to large foliose (leafy) lichens. It has a global distribution, extending from the Arctic to the Antarctic continent but concentrated in temperate regions. There are about 40 species in Parmelia. In recent decades, the once large genus Parmelia has been divided into a number of smaller genera according to thallus morphology and phylogenetic relatedness.
The Parmeliaceae is a large and diverse family of Lecanoromycetes. With over 2700 species in 71 genera, it is the largest family of lichen-forming fungi. The most speciose genera in the family are the well-known groups: Xanthoparmelia, Usnea, Parmotrema, and Hypotrachyna.
Lichenin, also known as lichenan or moss starch, is a complex glucan occurring in certain species of lichens. It can be extracted from Cetraria islandica. It has been studied since about 1957.
Ethnolichenology is the study of the relationship between lichens and people. Lichens have and are being used for many different purposes by human cultures across the world. The most common human use of lichens is for dye, but they have also been used for medicine, food and other purposes.
Bryoria fremontii is a dark brown, horsehair lichen that grows hanging from trees in western North America, and northern Europe and Asia. It grows abundantly in some areas, and is an important traditional food for a few First Nations in North America.
Parmotrema perlatum, commonly known as the powdered ruffle lichen, is a common species of foliose lichen in the family Parmeliaceae. The species has a cosmopolitan distribution and occurs throughout the Northern and Southern Hemispheres. Parmotrema perlatum is a prominent and widely recognised species within its genus across primarily temperate zones, preferring humid, oceanic-suboceanic habitats. It is found in diverse geographic areas including Africa, North and South America, Asia, Australasia, Europe, and islands in the Atlantic and Pacific oceans. It is usually grows on bark, but occasionally occurs on siliceous rocks, often among mosses.
Bamboo shoots or bamboo sprouts are the edible shoots of many bamboo species including Bambusa vulgaris and Phyllostachys edulis. They are used as vegetables in numerous Asian dishes and broths. They are sold in various processed shapes and are available in fresh, dried, and canned versions.
Lichens are symbiotic organisms made up of multiple species: a fungus, one or more photobionts and sometimes a yeast. They are regularly grouped by their external appearance – a characteristic known as their growth form. This form, which is based on the appearance of vegetative part of the lichen, varies depending on the species and the environmental conditions it faces. Those who study lichens (lichenologists) have described a dozen of these forms: areolate, byssoid, calicioid, cladoniform, crustose, filamentous, foliose, fruticose, gelatinous, leprose, placoidioid and squamulose. Traditionally, crustose (flat), foliose (leafy) and fruticose (shrubby) are considered to be the three main forms. In addition to these more formalised, traditional growth types, there are a handful of informal types named for their resemblance to the lichens of specific genera. These include alectorioid, catapyrenioid, cetrarioid, hypogymnioid, parmelioid and usneoid.
Isolichenan, also known as isolichenin, is a cold-water-soluble α-glucan occurring in certain species of lichens. This lichen product was first isolated as a component of an extract of Iceland moss in 1813, along with lichenin. After further analysis and characterization of the individual components of the extract, isolichenan was named in 1881. It is the first α-glucan to be described from lichens. The presence of isolichenan in the cell walls is a defining characteristic in several genera of the lichen family Parmeliaceae. Although most prevalent in that family, it has also been isolated from members of the families Ramalinaceae, Stereocaulaceae, Roccellaceae, and Cladoniaceae. Experimental studies have shown that isolichenan is produced only when the two lichen components – fungus and alga – are growing together, not when grown separately. The biological function of isolichenan in the lichen thallus is unknown.
Salazinic acid is a depsidone with a lactone ring. It is found in some lichens, and is especially prevalent in Parmotrema and Bulbothrix, where its presence or absence is often used to help classify species in those genera.
The following outline provides an overview of and topical guide to lichens.
