''Porphyra'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of coldwater

seaweed Seaweed, or macroalgae, refers to thousands of species of macroscopic, multicellular, marine algae. The term includes some types of ''Rhodophyta'' (red), '' Phaeophyta'' (brown) and ''Chlorophyta'' (green) macroalgae. Seaweed species such as ...

s that grow in cold, shallow

seawater Seawater, or sea water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has approximat ...

. More specifically, it belongs to

red algae Red algae, or Rhodophyta (, ; ), make up one of the oldest groups of eukaryotic algae. The Rhodophyta comprises one of the largest Phylum, phyla of algae, containing over 7,000 recognized species within over 900 Genus, genera amidst ongoing taxon ...

phylum of laver species (from which comes

laverbread Laverbread (; or '; ) is a food product made from laver, an edible seaweed (littoral alga) consumed mainly in Wales as part of local traditional cuisine. The seaweed is commonly found around the west coast of Great Britain, and the coasts of I ...

), comprising approximately 70 species.Brodie, J.A. and Irvine, L.M. 2003. ''Seaweeds of the British Isles.'' Volume 1 Part 3b. The Natural History Museum, London. It grows in the

intertidal zone The intertidal zone or foreshore is the area above water level at low tide and underwater at high tide; in other words, it is the part of the littoral zone within the tidal range. This area can include several types of habitats with various ...

, typically between the upper intertidal zone and the splash zone in cold waters of

temperate In geography, the temperate climates of Earth occur in the middle latitudes (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ran ...

oceans. In East Asia, it is used to produce the

sea vegetable Edible seaweed, or sea vegetables, are seaweeds that can be eaten and used for culinary purposes. They typically contain high amounts of fiber. They may belong to one of several groups of multicellular algae: the red algae, green algae, and brown ...

products ''

nori Nori is a dried edible seaweed used in Japanese cuisine, usually made from species of the red algae genus ''Pyropia'', including ''P. yezoensis'' and ''Pyropia tenera, P. tenera''. It has a strong and distinctive flavor, and is generally made in ...

'' (in Japan) and '' gim'' (in Korea). There are considered to be 60–70 species of ''Porphyra'' worldwide Kain, J.M. 1991. Cultivation of attached seaweeds. in Guiry, M.D. and Blunden, G. 1992. ''Seaweed Resources in Europe: Uses and Potential.'' John Wiley and Sons, Chichester and seven around Britain and Ireland, where it has been traditionally used to produce edible sea vegetables on the

Irish Sea The Irish Sea is a body of water that separates the islands of Ireland and Great Britain. It is linked to the Celtic Sea in the south by St George's Channel and to the Inner Seas off the West Coast of Scotland in the north by the North Ch ...

coast.Hardy, F.G. and Guiry, M.D. 2006. ''A Check-list and Atlas of the Seaweeds of Britain and Ireland.'' British Phycological Society, London. The species '' Porphyra purpurea'' has one of the largest

plastid A plastid is a membrane-bound organelle found in the Cell (biology), cells of plants, algae, and some other eukaryotic organisms. Plastids are considered to be intracellular endosymbiotic cyanobacteria. Examples of plastids include chloroplasts ...

genome A genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding genes, other functional regions of the genome such as ...

s known, with 251 genes.

Life cycle

''Porphyra'' displays a heteromorphic

alternation of generations Alternation of generations (also known as metagenesis or heterogenesis) is the predominant type of life cycle in plants and algae. In plants both phases are multicellular: the haploid sexual phase – the gametophyte – alternates with a diploi ...

. The

thallus Thallus (: 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. A thallus usually names the entir ...

we see is the

haploid Ploidy () is the number of complete sets of chromosomes in a cell (biology), cell, and hence the number of possible alleles for Autosome, autosomal and Pseudoautosomal region, pseudoautosomal genes. Here ''sets of chromosomes'' refers to the num ...

generation; it can reproduce asexually by forming

spore In biology, a spore is a unit of sexual reproduction, sexual (in fungi) or asexual reproduction that may be adapted for biological dispersal, dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores fo ...

s which grow to replicate the original thallus. It can also reproduce sexually. Both male and female

gamete A gamete ( ) is a Ploidy#Haploid and monoploid, haploid cell that fuses with another haploid cell during fertilization in organisms that Sexual reproduction, reproduce sexually. Gametes are an organism's reproductive cells, also referred to as s ...

s are formed on the one thallus. The female gametes while still on the thallus are fertilized by the released male gametes, which are non-motile. The fertilized, now

diploid Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Here ''sets of chromosomes'' refers to the number of maternal and paternal chromosome copies, ...

, carposporangia after

mitosis Mitosis () is a part of the cell cycle in eukaryote, eukaryotic cells in which replicated chromosomes are separated into two new Cell nucleus, nuclei. Cell division by mitosis is an equational division which gives rise to genetically identic ...

produce spores (

carpospore A carpospore is a diploid spore produced by red algae Red algae, or Rhodophyta (, ; ), make up one of the oldest groups of eukaryotic algae. The Rhodophyta comprises one of the largest Phylum, phyla of algae, containing over 7,000 recognized spe ...

s) which settle, then bore into shells, germinate and form a filamentous stage. This stage was originally thought to be a different species of alga, and was referred to as ''Conchocelis rosea''. That ''Conchocelis'' was the

stage of ''Porphyra'' was discovered in 1949 by the British phycologist

Kathleen Mary Drew-Baker Kathleen Mary Drew-Baker (née Drew; 6 November 1901 – 14 September 1957) was an English phycologist. She was known for her research on the edible seaweed ''Porphyra umbilicalis'', which led to a breakthrough for the commercial cultivation ...

for the

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

an species ''

Porphyra umbilicalis ''Porphyra umbilicalis'', commonly called "laver", is a species of seaweed in the genus ''Porphyra''. It is smooth in texture and forms delicate, sheetlike thalli, reaching long and often clinging to rocks. ''Porphyra'' is classified as red alga ...

''. It was later shown for species from other regions as well.Thomas, D. 2002. ''Seaweeds.'' The Natural History Museum, London.

Food

Most human cultures with access to use it as a food or somehow in the diet, making it perhaps the most domesticated of the marine algae,Mumford, T.F. and Miura, A. 4.''Porphyra'' as food: cultivation and economics. in Lembi, C.A. and Waaland, J.R. 1988. ''Algae and Human Affairs.'' Cambridge University Press, Cambridge. known as laver, (

Vietnamese Vietnamese may refer to: * Something of, from, or related to Vietnam, a country in Southeast Asia * Vietnamese people, or Kinh people, a Southeast Asian ethnic group native to Vietnam ** Overseas Vietnamese, Vietnamese people living outside Vietna ...

), ''

'' (

Japanese Japanese may refer to: * Something from or related to Japan, an island country in East Asia * Japanese language, spoken mainly in Japan * Japanese people, the ethnic group that identifies with Japan through ancestry or culture ** Japanese diaspor ...

:), ''amanori'' (Japanese), ''zakai'', '' gim'' (

Korean Korean may refer to: People and culture * Koreans, people from the Korean peninsula or of Korean descent * Korean culture * Korean language **Korean alphabet, known as Hangul or Korean **Korean dialects **See also: North–South differences in t ...

:), ''zǐcài'' (

Chinese Chinese may refer to: * Something related to China * Chinese people, people identified with China, through nationality, citizenship, and/or ethnicity **Han Chinese, East Asian ethnic group native to China. **'' Zhonghua minzu'', the supra-ethnic ...

:), karengo, ''sloke'' or ''slukos''. The marine red alga ''Porphyra'' has been cultivated extensively in many

Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...

n countries as an

edible seaweed Edible seaweed, or sea vegetables, are seaweeds that can be eaten and used for culinary purposes. They typically contain high amounts of fiber. They may belong to one of several groups of multicellular algae: the red algae, green algae, and bro ...

used to wrap the rice and fish that compose the Japanese food

sushi is a traditional Japanese dish made with , typically seasoned with sugar and salt, and combined with a variety of , such as seafood, vegetables, or meat: raw seafood is the most common, although some may be cooked. While sushi comes in n ...

and the Korean food ''

gimbap ''Gimbap'' (; ), also romanized as ''kimbap'', is a Korean cuisine, Korean dish made from Bap (rice dish), ''bap'' (cooked rice), vegetables, and optionally cooked seafood or meat, rolled in ''gim (food), gim''—dried sheets of seaweed—and s ...

''. In Japan, the annual production of ''Porphyra'' species is valued at 100 billion

yen The is the official currency of Japan. It is the third-most traded currency in the foreign exchange market, after the United States dollar and the euro. It is also widely used as a third reserve currency after the US dollar and the euro. T ...

(US$1 billion).Aoki, Y. and Kamei, Y. 2006 Preparation of recombinant polysaccharide-degrading enzymes from the marine bacterium, ''Pseudomonas'' sp. ND137 for the production of protoplasts of ''Porphyra yezoensis'' ''Eur. J. Phycol.'' 41: 321-328. is harvested from the coasts of Great Britain and Ireland, where it has a variety of culinary uses, including

. In Hawaii, "the species is considered a delicacy, called ". Porphyra was also harvested by the Southern Kwakiutl,

Haida Haida may refer to: Haida people Many uses of the word derive from the name of an indigenous people of the Pacific Northwest Coast of North America. * Haida people, an Indigenous ethnic group of North America (Canada) ** Council of the Haida Nati ...

, Seechelt, Squawmish,

Nuu-chah-nulth The Nuu-chah-nulth ( ; ), also formerly referred to as the Nootka, Nutka, Aht, Nuuchahnulth or Tahkaht, are one of the Indigenous peoples of the Pacific Northwest Coast in Canada. The term Nuu-chah-nulth is used to describe fifteen related tri ...

Nuxalk The Nuxalk people (Nuxalk language, Nuxalk: ''Nuxalkmc''; pronounced )'','' also referred to as the Bella Coola, Bellacoola or Bilchula, are an Indigenous peoples of the Pacific Northwest Coast, Indigenous First Nations in Canada, First Nation ...

Tsimshian The Tsimshian (; ) are an Indigenous peoples of the Pacific Northwest Coast, Indigenous people of the Pacific Northwest Coast of North America. Their communities are mostly in coastal British Columbia in Terrace, British Columbia, Terrace and ...

, and

Tlingit The Tlingit or Lingít ( ) are Indigenous peoples of the Pacific Northwest Coast of North America. , they constitute two of the 231 federally recognized List of Alaska Native tribal entities, Tribes of Alaska. Most Tlingit are Alaska Natives; ...

peoples of the North American Pacific coast.

Vitamin B12

''Porphyra'' contains

vitamin B12 Vitamin B12, also known as cobalamin, is a water-soluble vitamin involved in metabolism. One of eight B vitamins, it serves as a vital cofactor (biochemistry), cofactor in DNA synthesis and both fatty acid metabolism, fatty acid and amino a ...

and one study suggests that it is the most suitable non-meat source of this essential vitamin. In the view of the Academy of Nutrition and Dietetics, however, it may not provide an adequate source of B12 for

vegan Veganism is the practice of abstaining from the use of animal products and the consumption of animal source foods, and an associated philosophy that rejects the commodity status of animals. A person who practices veganism is known as a ve ...

Species

''Porphyra'' currently contains 57 confirmed species and 14 unconfirmed species.

Confirmed

Unconfirmed

Following a major reassessment of the genus in 2011, many species previously included in ''Porphyra'' have been transferred to ''

Pyropia ''Pyropia'' is a genus of red algae in the family Bangiaceae. It is found around the world in intertidal zones and shallow water. The genus has folding frond-like blades which are either red, brown or green. Some ''Pyropia'' species are used to ...

'': for example '' Pyropia tenera'', '' Pyropia yezoensis'', and the species from New Zealand '' Pyropia rakiura'' and '' Pyropia virididentata'', leaving only five species out of seventy still within ''Porphyra'' itself.

References

External links

* *
Video footage of Laverbread or Bara Lawr
{{Authority control Red algae genera Bangiophyceae Edible seaweeds Seaweeds Edible algae Taxa named by Carl Adolph Agardh