Knotted Wrack - Ascophyllum Nodosum

Knotted wrack belongs to a group of seaweeds which often dominate the rocky shore around Lundy and various characteristics make it an easily identifiable seaweed of the shore.

Attached firmly by a disc-like holdfast, several narrow long fronds arise which can grow to about one metre in length and longer in very sheltered situations.  At intervals along the frond single egg-like air bladders grow, and whch gives rise to its other name 'egg wrack'.  The seaweed produces about one of these bladders every year which makes it possible to estimate the age of the seaweed by counting a series of bladders.  The bladder's main purpose is to hold the plant afloate in the water to gain maximum light.   In summer small reproductive organs grow on short side branches.

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