Wild Harris

Knotted Wrack

Recognised by its long strap-like leaves with single bladders at intervals along it, and on the side branches.

ascophyllum 1.jpgKnotted Wrack    (Photo: Paul Tyler)

Knotted wrack, the weed that once brought great wealth to the island landlords. You can tell its age by counting the air bladders on the main stalk - it adds a new one each year.

finsbay ascophyllum.jpgKnotted Wrack: Finsbay    (Photo: Paul Tyler)

In very sheltered locations such as Finsbay, knotted wrack grows in great profusion

ascophylluh nodosoh.jpgKnotted Wrack Submerged    (Photo: Sue Scott)

How knotted wrack looks when the tide is in.

Knotted wrack is present in huge quantities around the shores of sheltered sealochs, and has been harvested over the centuries to extract the valuable chemicals that it contains. These have included soda for making glass, iodine for medicine and jelly-like alginates which are used in the manufacture of everything from textile dyes, ice cream and welding rods! The seaweed industry has seen many cycles of boom and bust over the years, and is currently seeing a revival with a new processing plant near Stornoway, which takes hand cut and machine cut weed from several sites in Lewis and Harris.


seaweed cutting machine.jpg(Photo: Paul Tyler)

A mechanical seaweed cutter currently operating on the island.  This weed is also collected by crofters and put on their lazybeds as fertiliser to help their crops grow.

by Paul Tyler