Undaria pinnatifida

Undaria pinnatifida

Undaria pinnatifida is a large brown seaweed belonging to the order Laminariales, with 3 clearly recognizable parts comprising its visible thallus: blade, stipe, and holdfast.  The thallus can reach 1 to 3 meters in length.  The blade is lanceolate and broad with a prominent midrib, and translucent with color ranging from green to yellowish-brown to dark brown.  The blade could also be described as triangular and lobed.  The appearance of the blade evolves and changes over time; it is initially simple, flattened, and broad with a pronounced or distinct midrib; older plants have thicker blade tissue which splits horizontally down to the midrib to form fingers or straps, becoming more transversally lobed, and becomes pinnate with age.  The margins of the blade can also be described as wavy.  The distal portion of the blade and the straps eventually become tattered.  The stipe of Undaria pinnatifida is wavy or corrugated above the holdfast.  The stipe is also usually short (10 to 30 centimeters in length, and up to 1 centimeter in diameter) and in mature plants bears convoluted wing-like reproductive outgrowths or frills (sporophylls).  The stipe is also flattened, and transitions into the midrib which extends through the middle of the length of the blade.  Undaria pinnatifida attaches to its substrate by a branched holdfast comprised of haptera.  It may be confused with Alaria esculenta, as it also has a prominent midrib, but the corrugated stipe of Undaria pinnatifida (which contains its sporophylls) is distinctive.  Also, Alaria esculenta grows in more exposed and wave-battered locations than Undaria pinnatifida.

Undaria pinnatifida can be found in the upper part of the infralittoral (subtidal) zone, from low tide level down to depths of 10 to 18 meters.  If the water is clear and less turbid, it can grow at deeper depths.  In its native habitat, Undaria pinnatifida occurs in dense stands, forming a thick canopy on a wide range of shores.  Undaria pinnatifida prefers areas with less exposure, such as in ports.  It can attach itself to substrates which are natural (bedrock, boulders) and artificial (such as pilings, port structures, marina pontoons, buoys, or anchor chains).  Undaria pinnatifida is able to tolerate a range of organic pollution, salinity levels, and temperatures.  It can grow well in esturarine conditions as well.  Undaria pinnatifida spreads in two ways: naturally, through the millions of microscopic spores released by each fertile organism, and also through attachment to vessel hulls and marine farming equipment.  Undaria pinnatifida is a highly successful and fertile species, which enable it to expand it range quickly.

Image Gallery

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underwater photo of large Undaria pinnatifida seaweed plant by Janna Nichols

underwater photo of Undaria pinnatifida seaweed by Janna Nichols

closeup underwater photo of Undaria pinnatifida seaweed by Yann Fontana, Station Biologique de Roscoff

photo of Undaria pinnatifida seaweed by Dr. Keith Hiscock, with assistance from the Marine Life Information Network

closeup underwater photo of Undaria pinnatifida seaweed by Anne Frijsinger and Mat Vestjens



abeto marino, ao-wakame, 青若布, apron-ribbon vegetable, Asian kelp, fougère de mer, fougère des mers, haijiecai, harmonica wier, hira-wakame, ito-wakame, 糸若布, Japanese kelp, Japonaise wakame, Japanse kelp, kada-me, kuki wakame, miyeok, miyeuk, miyok, 미역, nambu wakame, naruto wakame, niki-me, Ouessane, quandaicai, qun dai cai, qúndài cài, 裙带菜, sea mustard, wakame, Wakame, wakamé, ワカメ, わかめ, 若布, 和布

Phylum Classification 
Geographic Distribution 

Undaria pinnatifida is a laminarian kelp indigenous to the northwest Pacific Ocean and the cold temperate coastal regions of Japan, China, Korea, and southeast Russia.  Undaria pinnatifida has been spread around the world by international shipping and mariculture, and has extended its range to include four continents since 1980's.  It is now growing in the temperate Pacific Ocean, the southeastern temperate Indian ocean, the Mediterranean, and the temperate north and south Atlantic Ocean.

Countries where Undaria pinnatifida has emerged since the 1980s include Argentina, United States, Mexico, France, Great Britain, Spain, Italy, Belgium, Australia, and New Zealand.


Undaria pinnatifida has a high nutritional value, containing high levels of calcium, iodine, thiamine, niacin, iron, vitamin B12, and protein.  It is also a rich source of eicosapentaenoic acid, an omega-3 fatty acid, and also of polysaccharides.  A compound in Undaria pinnatifida known as fucoxanthin can help burn fatty tissue, even around internal organs.  In Oriental medicine, Undaria pinnatifida has been used for blood purification, intestinal strength, skin, hair, reproductive organs and menstrual regularity.

Undaria pinnatifida is economically important as a food crop, next to nori, on the Japanese menu, and is eaten both dried and fresh.  In East Asian countries the seaweed is known as wakame and is treated as a delicacy, often added to miso soup.  Undaria pinnatifida can be considered a a sea vegetable, or edible seaweed.  "Wakame" fronds are green and have a subtly sweet flavour and slippery texture.  In Asia and Europe, wakame is distributed either dried or salted, and used in soups (particularly miso soup), and salads (such as tofu salad), or often as a side dish to tofu and a salad vegetable like cucumber.  Goma wakame, also known as seaweed salad, is a popular side dish at some sushi restaurants; literally translated, it means "sesame seaweed".  In Korea, Undaria pinnatifida is used in salads or soup such miyeokguk.  Many women consume Undaria pinnatifida during pregnancy, and "miyeokguk" is popularly consumed by women after giving birth as miyeok contains a high content of calcium and iodine, nutrients that are important for nursing new mothers.  It is also traditionally eaten on birthdays for this reason, a reminder of the first food that the mother has eaten and passed on to her newborn through her milk, thus bringing good fortune for the rest of the year.  After the species was accidentally introduced in 1971 in the Mediterranean via farming of Japanese oysters (Crassostrea gigas), Undaria pinnatifida was grown in the French Bretagne as food, which increased exposure of this seaweed to Europeans.  Undaria pinnatifida is also used in a wide variety of topical beauty treatments and personal care products, due to its high polysaccharide content and ability to provide moisture.

Undaria pinnatifida is an ingredient in dozens of products from countries which include France, Italy, UK, Spain, China, Japan, Korea, New Zealand, Australia, Canada, and the United States.   Health and personal care products including Undaria pinnatifida as an ingredient include:

  • Shampoo, hair treatments, and bath treatments
  • hand and foot care products
  • soaps, body polishes and oils
  • skin cleanser and toner products, detoxifying facial products
  • day creams and night creams
  • tooth cleaning products

There are many forms of edible Undaria pinnatifida, or wakame, including:

  • dried, chips, flakes, and strips
  • as an ingredient in sea vegetable salads, in condiments and chutneys
  • with soup and salad and pasta and oatmeal mixes
  • capsule form as a diet supplement
  • beer

Undaria pinnatifida is also included in some fertilizers and agricultural treatments.


Sea farmers have grown Undaria pinnatifida for hundreds of years in Korea and Japan, and in more recent years there has been expansive growth in China, where production is concentrated around Dalian.  Since 1983 Undaria pinnatifida has also been cultivated in France, in sea fields established near the shores of Brittany, where it is harvested in March and April.  Wild grown Undaria pinnatifida is known to be harvested in Tasmania, Australia and in New Zealand for commercial products.  Undaria pinnatifida is also cultivated in Brittany, France, where it was imported several years ago.

Harvesting Techniques 

When farmed, Undaria pinnatifida is usually harvested from boats by means of long hooks and then sold fresh or sun dried.  In some cases, since this seaweed is salted for transport, certain cleansing must take place before eating; is must be thoroughly rinsed under running water, then placed in boiling water for a short time, then rinsed in ice water.  The leaves of Undaria pinnatifida are then spread out and the hard midrib removed.


Undaria pinnatifida can grow in the same zones as Saccorhiza polyschides, Sargassum muticum, and different species of Cystoseira.  It can form dense kelp forests.  At the end of the season, its blade may become covered by colonial animals, as it is effective in providing habitats, nursery areas and protective cover for many species.  In areas where Undaria pinnatifida has been introduced, it may change the structure and composition of native marine communities.