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DescriptionA large conspicuous kelp which can grow up to 3.5 m in length in suitable conditions although this length is rarely attained (J. Jones, pers. comm.). The blade is broad, large, tough, flat and divided into 5 - 20 straps or fingers (digitate). The blade is glossy, golden brown to very dark brown in colour. The holdfast is large, conical and branched with conspicuous haptera. The stipe is stiff, rough textured, thick at the base and tapers towards the frond. The stipe stands erect when out of water. The stipe is often covered with numerous epifauna and epiflora. The amount of energy allocated to growth of the stipe, and consequently maximum length of stipe, varies with season, the age of plant and location. This species is often confused with Laminaria digitata, especially when young.Other common names include, redware, cuvy, sea rod, mayweed or Slat mara. The new blade grows below the older from November onwards. The old blade is shed in spring and early summer. Blade and stipe vary with exposure and current. In sheltered conditions the blade has few or no digits and the stipe becomes thin but in exposed conditions the blade is deeply digitate and the stipe becomes thick. The stipe is usually up to 1m long but stipes up to 3m long have been recorded (Parke unpublished, cited in Kain, 1971a).