Laminaria

Laminaria is a genus of 31 species of brown algae (Phaeophyceae) all sharing the common name "kelp". This economically important genus is noted for being a long, leathery giant seaweed. Some species are referred to by the common name Devil's apron, due to their shape, or sea colander due to the perforations present on the lamina. It is found in the north Atlantic Ocean and the northern Pacific Ocean at depths from 8 m to 30 m (exceptionally to 120 m in the warmer waters of the Mediterranean Sea and off Brazil).

The life history of Laminaria shows two stages. An alteration between a large diploid sporophyte and a very small, microscopic, haploid microthallus. The large phase is a diploid sporophyte, after meiosis it produces gametes with flagella. Half of these grow into male and half into female gametophytes. They grow to form microscopic branched filaments. The male gametophytes bear small unicellular antheridia which fertilize the egg cell which is extruded from the oogonium, but remains attached to it. The zygote then develops and grows to become the sporophyte.

Laminaria is used in the production of potassium chloride and iodine. Dried laminaria sticks can be used medicinally to induce dilation of the cervix. It is also a nutritious food. The species Laminaria japonica is the main component of the Japanese food kombu.

Species
There are around 30 species in the genus Laminaria some of which are sometimes split off as the genus Saccharina:
 * Laminaria abyssalis A.B. Joly & E.C. Oliveira — Atlantic South America
 * Laminaria agardhii Kjellman — Atlantic North America
 * Laminaria angustata Kjellman — Japan
 * Laminaria appressirhiza J. E. Petrov & V. B. Vozzhinskaya
 * Laminaria brasiliensis A. B. Loly & E. C. Oliveira
 * Laminaria brongardiana Postels & Ruprecht
 * Laminaria bulbosa J. V. Lamouroux
 * Laminaria bullata Kjellman
 * Laminaria complanata (Setchell & N. L. Garder) Muenscher
 * Laminaria dentigera Kjellm. — North American Pacific: Bering Strait to Baja California
 * Laminaria diabolica Miyabe
 * Laminaria digitata (Hudson) J. V. Lamouroux
 * Laminaria ephemera Setchell — North American Pacific: Vancouver to California
 * Laminaria farlowii Setchell — North American Pacific shores
 * Laminaria hyperborea (Gunnerus) Foslie
 * Laminaria inclinatorhiza J. Petrov & V. Vozzhinskaya
 * Laminaria japonica J. E. Areschoug — Japan
 * Laminaria multiplicata J. Petrov & M. Suchovejeva
 * Laminaria nigripes J. Agardh
 * Laminaria ochroleuca Bachelot de la Pylaie
 * Laminaria pallida Greville — South Africa, Indian Ocean, Canary Islands and Tristan da Cunha
 * Laminaria platymeris Bachelot de la Pylaie
 * Laminaria rodriguezii Barnet
 * Laminaria ruprechtii (Areschoug) Setchell
 * Laminaria saccharina (Linnaeus) J.V. Lamouroux
 * Laminaria sachalinensis (Miyabe) Miyabe
 * Laminaria setchellii P. C. Silva
 * Laminaria sinclairii (Harvey ex J. D. Hooker & Harvey) Farlow, Anderson & Eaton — North America Pacific shores
 * Laminaria solidugula J. Agardh
 * Laminaria yezoensis Miyabe

British Isles
Four species of Laminaria have been recorded from the British Isles — Laminaria digitata, L. hyperborea, L. ochroleuca and L. saccharina; the occurrence of Laminaria longricruris in the British Isles has not yet been confirmed.