Knotted wrack

Picture of knotted wrack

Distribution in scandinavian waters

Maximum length: Knotted wrack can under certain circumstances be over 2 m long, but normally is seldom longer than 0,3-1 m.
Appearance: The plant is quite slender, dense with belt like torso pockets that branch irregularly. Along the whole of the branch small air filled bladders are regularly situated. They are not situated in pairs, but individually. The root is robust. Male and female reproductive organs develope on different individuals. Knotted wrack varies in colour, from yellow to olive-green. Compare knotted wrack with bladder wrack.
Depth: From sea level to a depth of about 2 m. Quite often, knotted wrack builds banks between bladder and toothed wrack.
Environment: Found on cliffs and large rocks that are wave protected, but where water exchange is still good.
Misc: Have you noticed the strange marks on the plant pictured above? These have probably been caused by a grazing periwinkle.
Classification: Knotted wrack is a member of the brown algae group.

Knotted wrack     Other names

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Bo Johannesson | Martin Larsvik | Lars-Ove Loo | Helena Samuelsson