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Porphyra is a coldwater seaweed that grows in cold, shallow seawater. More specifically, it belongs to red algae phylum of laver species (from which comes laverbread), comprising approximately 70 species. It grows in the intertidal zone, typically between the upper intertidal zone and the splash zone in cold waters of temperate oceans. In East Asia, it is used to produce the sea vegetable products nori (in Japan) and gim (in Korea). There are considered to be 60 to 70 species of Porphyra worldwide and seven around Britain and Ireland where it has been traditionally used to produce edible sea vegetables on the Irish Sea coast. Porphyra is a chief source of plant-based vitamin B12.
Porphyra displays a heteromorphic alternation of generations. The thallus we see is the haploid generation; it can reproduce asexually by forming spores 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, carposporangia after mitosis 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 diploid stage of Porphyra was discovered by the British phycologist Kathleen Mary Drew-Baker in 1949 for the European species Porphyra umbilicalis. It was later shown for species from other regions as well.
Most human cultures with access to Porphyra use it as a food or somehow in the diet, making it perhaps the most domesticated of the marine algae, known as laver, rong biển (Vietnamese), nori (Japanese:海苔), amanori (Japanese), zakai, gim (Korean:김), zǐcài (Chinese:紫菜), 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).
P. umbilicalis is harvested from the coasts of Great Britain and Ireland, where it has a variety of culinary uses including laverbread. In Hawaii, "the species P. atropurpurea is considered a great delicacy, called Limu luau". Porphyra was also harvested by the Southern Kwakiutl, Haida, Seechelt, Squawmish, Nuu-chah-nulth, Nuxalk, Tsimshian, and Tlingit peoples of the North American Pacific coast.
Source of Vitamin B12
One study in 2014 pointed to dried purple laver as a vegan source of biologically-active Vitamin B12. The study noted that B-12 was found in both raw and roasted seaweed, the latter containing about half as much—but still a sufficient amount. Just 4 grams of dried purple laver was considered sufficient to meet the RDA for B-12. However, the Academy of Nutrition and Dietetics considers this source unreliable for vegans.
This section is missing information about what the five species are and where all others went.April 2020)(
- Porphyra akasakae A.Miura 1977
- Porphyra angusta Okamura & Ueda 1932
- Porphyra argentinensis M.L.Piriz 1981
- Porphyra atropurpurea (Olivi) De Toni 1897
- Porphyra augustinae Kützing 1843
- Porphyra autumnalis Zanardini 1860
- Porphyra bangiaeformis Kützing 1849
- Porphyra bulbopes (Yendo) Ueda 1932
- Porphyra capensis Kützing 1843
- Porphyra carnea Grunow 1889
- Porphyra ceylanica J.Agardh 1883
- Porphyra chauhanii C.Anil Kumar & M.V.N.Panikkar 1995
- Porphyra corallicola H.Kucera & G.W. Saunders 2012
- Porphyra cordata Meneghini 1844
- Porphyra cucullata De Notaris 1865
- Porphyra delicatula Welwitsch
- Porphyra dentimarginata Chu Chia-yen & Wang Su-chuan 1960
- Porphyra dioica J.Brodie & L.M.Irvine 1997
- Porphyra drewiae M.K.Elias 1966
- Porphyra fujianensis Zhang & Wang 1993
- Porphyra grateloupicola P.L.Crouan & H.M.Crouan 1878
- Porphyra grayana Reinsch 1875
- Porphyra guangdongensis C.K.Tseng & T.J.Chang 1978
- Porphyra haitanensis T.J.Chang & B.F.Zheng 1960
- Porphyra hospitans Zanardini 1855
- Porphyra inaequicrassa L.P.Perestenko 1980
- Porphyra indica V.Krishnamurthy & M.Baluswami 1984
- Porphyra ionae R.W.Ricker 1987
- Porphyra irregularis E.Fukuhara 1968
- Porphyra kanyakumariensis V.Krishnamurthy & M.Baluswami 1984
- Porphyra laciniata C.Agardh 1824
- Porphyra ledermannii Pilger 1911
- Porphyra linearis Greville 1830
- Porphyra lucasii Levring 1953
- Porphyra maculosa E.Conway 1976
- Porphyra malvanensis Anilkumar & P.S.N.Rao 2005
- Porphyra marcosii P.A.Cordero 1976
- Porphyra marginata C.K.Tseng & T.J.Chang 1958
- Porphyra martensiana Suhr 1840
- Porphyra microphylla Zanardini 1860
- Porphyra microphylla Reinsch 1878
- Porphyra minima P.Crouan & H.Crouan 1842
- Porphyra minor Zanardini 1847
- Porphyra monosporangia S.Wang & J.Zhang 1980
- Porphyra mumfordii S.C.Lindstrom & K.M.Cole 1992
- Porphyra njordii P.M.Pedersen 2011
- Porphyra nobilis J.Agardh 1883
- Porphyra nobilis De Notaris 1846
- Porphyra ochotensis Nagai 1941
- Porphyra okamurae Ueda 1932
- Porphyra okhaensis H.V.Joshi R.M.Oza & A.Tewari 1992
- Porphyra oligospermatangia C.K.Tseng & B.F.Zheng 1981
- Porphyra plocamiestris R.W.Ricker 1987
- Porphyra pujalsiae Coll & E.C.Oliveira 1976
- Porphyra pulchra Hollenberg 1943
- Porphyra punctata Y.Yamada & H.Mikami 1956
- Porphyra purpurea (Roth) C.Agardh 1824
- Porphyra qingdaoensis C.K.Tseng & B.F.Zheng 1988
- Porphyra ramosissima Pan & Wang 1982
- Porphyra reniformis Meneghini 1849
- Porphyra rizzinii Coll & E.C.Oliveira 1976
- Porphyra roseana M.A.Howe 1928
- Porphyra schistothallus B.F.Zheng & J.Li
- Porphyra segregata (Setchell & Hus) V.Krishnamurthy 1972
- Porphyra tenuis B.F.Zheng & J.Li
- Porphyra tenuissima (Strömfelt) Setchell & Hus 1900
- Porphyra tenuissima C.Agardh ex Frauenfeld 1855
- Porphyra tristanensis Baardseth 1941
- Porphyra umbilicalis Kützing 1843
- Porphyra umbilicata Ruprecht 1850
- Porphyra violacea J.Agardh 1899
- Porphyra vulgaris Kützing 1843
- Porphyra woolhouseae Harvey 1863
- Porphyra yamadae Yoshida 1997
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 yezoensis and the species from New Zealand Pyropia rakiura and Pyropia virididentata, leaving only five species out of seventy still within Porphyra itself.
- Guiry, Michael D. (2012). Porphyra. In: Guiry, M.D. & Guiry, G.M. (2017). AlgaeBase. World-wide electronic publication, National University of Ireland, Galway (taxonomic information republished from AlgaeBase with permission of M.D. Guiry). Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=143808 on 2017-09-06
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- 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 ISBN 0-471-92947-6
- Hardy, F.G. and Guiry, M.D. 2006. A Check-list and Atlas of the Seaweeds of Britain and Ireland. British Phycological Society, London. ISBN 3-906166-35-X
- Porphyra life cycle Archived 2007-04-11 at the Wayback Machine
- Drew, Kathleen M. (1949). "Conchocelis-phase in the life-history of Porphyra umbilicalis (L.) Kütz". Nature. 164 (4174): 748–749. Bibcode:1949Natur.164..748D. doi:10.1038/164748a0.
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- Abbott, Isabella A (1989). Lembi, Carole A.; Waaland, J. Robert (eds.). Algae and human affairs (Food and food products from seaweeds). Cambridge University Press, Phycological Society of America. p. 141. ISBN 978-0-521-32115-0. CS1 maint: discouraged parameter (link)
- 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.
- "Laver Seaweed – A Foraging Guide to Its Food, Medicine and Other Uses". eatweeds.co.uk. Retrieved 22 March 2021.
- Watanabe, Fumio; Yabuta, Yukinori; Bito, Tomohiro; Teng, Fei (2014-05-05). "Vitamin B12-Containing Plant Food Sources for Vegetarians". Nutrients. 6 (5): 1861–1873. doi:10.3390/nu6051861. ISSN 2072-6643. PMC 4042564. PMID 24803097.
- Melina V, Craig W, Levin S (2016). "Position of the Academy of Nutrition and Dietetics: Vegetarian Diets". J Acad Nutr Diet. 116 (12): 1970–1980. doi:10.1016/j.jand.2016.09.025. PMID 27886704.
Fermented foods (such as tempeh), nori, spirulina, chlorella algae, and unfortified nutritional yeast cannot be relied upon as adequate or practical sources of B-12.39,40 Vegans must regularly consume reliable sources— meaning B-12 fortified foods or B-12 containing supplements—or they could become deficient, as shown in case studies of vegan infants, children, and adults.
- Morton, O. 1994. Marine Algae of Northern Ireland. Ulster Museum, Belfast. ISBN 0-900761-28-8
- Sutherland; et al. (October 2011). "A New Look at an Ancient Order: Generic Revision of the Bangiales (Rhodophyta)". J. Phycol. 47 (5): 1131–1151. doi:10.1111/j.1529-8817.2011.01052.x. PMID 27020195.