''Porphyra'' is a genus 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. More specifically, it belongs to

red algae Red algae, or Rhodophyta (, ; ), are one of the oldest groups of eukaryotic algae. The Rhodophyta also comprises one of the largest phyla of algae, containing over 7,000 currently recognized species with taxonomic revisions ongoing. The majority ...

phylum of laver species (from which comes

laverbread Laverbread (; cy, bara lafwr or '; ga, sleabhac) 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 ...

), 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, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species o ...

, typically between the upper intertidal zone and the

splash zone In offshore construction, the splash zone is the transition from air to water when lowering heavy burdens into the sea. The overall efforts applied on the crane change dramatically when the load starts touching water, up to the point where it is ...

in cold waters of temperate 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 ...

products '' nori'' (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 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 ''Porphyra purpurea'' is a medium sized marine algae in the Division Rhodophyta. Description This red algae consists of a single membranous layer of cells forming a blade attached by a disk holdfast (biology), holdfast. It grows to a length of 2 ...

'' has one of the largest

plastid The plastid (Greek: πλαστός; plastós: formed, molded – plural plastids) is a membrane-bound organelle found in the Cell (biology), cells of plants, algae, and some other eukaryotic organisms. They are considered to be intracellular endosy ...

genomes 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 Biological life cycle, life cycle in plants and algae. It consists of a Multicellular organism, multicellular haploid sexual phase, the gametophy ...

. The thallus we see is the

haploid Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectively ...

generation; it can reproduce asexually by forming

spore In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, f ...

s which grow to replicate the original thallus. It can also reproduce sexually. Both male and female gametes 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. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectively ...

, carposporangia after

mitosis In cell biology, mitosis () is a part of the cell cycle in which replicated chromosomes are separated into two new nuclei. Cell division by mitosis gives rise to genetically identical cells in which the total number of chromosomes is mainta ...

produce spores ( carpospores) 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 for the European species ''

Porphyra umbilicalis Green laver (), known as ''aonori'' (; ) in Japan, ''sea cabbage'' () or ''hutai'' () in China, and ''parae'' () in Korean, is a type of edible green seaweed, including species from the genera ''Monostroma'' and ''Ulva'' ('' Ulva prolifera'', '' ...

''. 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 Laver may refer to: * Laver (surname), a list of people with the name * Laver (ghost town), Sweden * Green laver, a type of edible green seaweed used to make laverbread * River Laver, a river in North Yorkshire, England * Lavatorium, a washing fa ...

, ( Vietnamese), '' nori'' ( Japanese:), ''amanori'' (Japanese), ''zakai'', '' gim'' ( Korean:), ''zǐcài'' (

Chinese Chinese can refer to: * Something related to China * Chinese people, people of Chinese nationality, citizenship, and/or ethnicity **''Zhonghua minzu'', the supra-ethnic concept of the Chinese nation ** List of ethnic groups in China, people of va ...

:), karengo, ''sloke'' or ''slukos''. The marine red alga ''Porphyra'' has been cultivated extensively in many Asian countries as an edible seaweed used to wrap the rice and fish that compose the Japanese food sushi and the Korean food '' gimbap''. In Japan, the annual production of ''Porphyra'' species is valued at 100 billion yen (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 Laich-kwil-tach (also spelled Ligwilda'xw), is the Anglicization of the Kwak'wala autonomy by the "Southern Kwakiutl" people of Quadra Island and Campbell River in British Columbia, Canada. There are today two main groups (of perhaps five origi ...

Haida Haida may refer to: Places * Haida, an old name for Nový Bor * Haida Gwaii, meaning "Islands of the People", formerly called the Queen Charlotte Islands * Haida Islands, a different archipelago near Bella Bella, British Columbia Ships * , a 1 ...

, Seechelt, Squawmish, Nuu-chah-nulth, Nuxalk, Tsimshian, and Tlingit peoples of the North American Pacific coast.

Vitamin B12

''Porphyra'' contains vitamin B12 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 vegans.

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'': for example ''

Pyropia tenera ''Pyropia tenera'', also known as gim or nori, is a red algal species in the genus ''Pyropia''. The specific name, ''tenera'', means "delicate" and alludes to its small size. It typically grows to lengths between 20 and 50 cm. It is most ...

'', ''

Pyropia yezoensis ''Pyropia'' is a genus of red algae eaweedin 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 us ...

'', and the species from New Zealand ''

Pyropia rakiura ''Pyropia rakiura'', formerly known as ''Porphyra rakiura'', is a red alga species in the genus ''Pyropia'', known from New Zealand. It is monostromatic, monoecious, and grows in the intertidal zone, predominantly on rock substrata. With '' P. c ...

'' and ''

Pyropia virididentata ''Pyropia virididentata'', formerly known as ''Porphyra virididentata'', is a red alga species in the genus ''Pyropia.'' It is endemic to New Zealand. It is monostromatic, monoecious, and grows in the intertidal zone, predominantly on rock subs ...

'', 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