Oarweed (Laminaria digitata)

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Oarweed stipes and fronds

Top facts

  • Oarweed is a species of kelp which can grow up to two metres in length.
  • Oarweed attaches to stones and rocky substrates with a holdfast, and can endure the full force of heavy waves.
  • Oarweed has many uses. Traditionally harvested as a fertiliser, it is also used for cooking and in the manufacturing of cosmetics.
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Oarweed fact file

Oarweed description

KingdomProtista
PhylumPhaeophyta
ClassPhaeophyceae
OrderLaminariales
FamilyLaminariaceae
GenusLaminaria (1)

Oarweed (Laminaria digitata), also known as 'tangle' or 'tangleweed' is a familiar glossy golden brown kelp, which grows attached to rocky substrates with a dome-shaped cluster of root-like holdfasts (3). The smooth and flexible stipe (stem) is oval in cross-section, and gives rise to a broad frond that is divided into ribbon-like segments and lacks a midrib (2).

Size
Length: up to 2 m (2)
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Oarweed biology

This perennial species lives for 4-6 years (2). New growth occurs at the base of the stipe, where it joins to the frond; although growth occurs throughout the year, it seems to be fastest during the spring (3).Kelp beds are important habitats for many other species (2).

Kelps have been used by humans as a source of chemicals, as agricultural fertilisers, and for culinary uses (2).

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Oarweed range

Occurs around the coasts of Britain, but is scarce along parts of the east coast due to a lack of hard substrates and turbidity of the water (2). Elsewhere it is known from the Atlantic coasts of Europe, as well as from Iceland, southern Greenland and the eastern coasts of North America (2).

You can view distribution information for this species at the National Biodiversity Network Gateway.
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Oarweed habitat

This kelp is characteristic of the lower intertidal and shallow subtidal zones (4), and can reach a depth of 20m in clear water (2). It seems to fare particularly well in moderately exposed areas or where there are strong water currents (2).

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Oarweed status

Common and widespread.

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Oarweed threats

This seaweed is not currently threatened.

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Oarweed conservation

No conservation action has been targeted at this species.

There may be further information about this species available via the National Biodiversity Network Gateway.
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Find out more

For more on this species see the Marine Link Information Network (MarLIN) species account:
http://www.marlin.ac.uk/species/Laminariadigitata.htm

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Authentication

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk

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Glossary

Perennial
Plants that live for at least three seasons; after an initial period they produce flowers once a year.
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References

  1. National Biodiversity Network Species Dictionary (November, 2002)
    http://www.nhm.ac.uk/nbn/
  2. Hill, J.M., 2000. Laminaria digitata. Oarweed. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. (August, 2002)
    http://www.marlin.ac.uk/species/Laminariadigitata.htm
  3. Fish, J.D. and Fish, S. (1996) A student's guide to the seashore. Second Edition. Cambridge University Press, Cambridge.
  4. The Seaweed Site. Michael D. Guiry (November, 2002)
    http://www.seaweed.ie/descriptions/Lamdig.html
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Image credit

Oarweed stipes and fronds  
Oarweed stipes and fronds

© lauriecampbell.com

Laurie Campbell Photography
Hestia
Paxton
Berwick-upon-Tweed
TD15 1TE
United Kingdom
Tel: +44 (0) 1289 386 736
Fax: +44 (0) 1289 386 746
info@lauriecampbell.com
http://www.lauriecampbell.com

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