Oarweed

Laminaria digitata

Laminaria digitata

Laminaria digitata

The great beds of kelp that wash up on the beach of high tide are often composed of great knots of Oarweed, the fingered rubbery kelps that blanket the edge of the low tide mark, their slippery leather-strap blades twisted around thickened stipes ending in gnarled and crusty holdfasts.

Also known as ‘sea girdles’ and tangle, on days of the lowest tides you can see dense meadows that stretch from the low-lying reefs out to bigger rocks and small islands in the bay. Growing to about 3 metres in length, they may have from 5 to 20 ‘fingers’ (depending on their age and location). Laminaria need a hard substrata to hold onto, and prefer to have their feet deep in rock pools and crevices, so will not spread to sandy shorelines, although at times they get this wrong and are clutching small stones when washed ashore. The are distinguishable from their close relative, the Laminaria hyperborea, by their smaller size and their relatively skinny, circular stipes which tend to be shiny and clean of epiphytic Rhodophyta.

Laminaria digitata

Laminaria digitata

Edible, Laminaria digitata, like all other kelps, is a rich source of minerals, vitamins and trace elements (including iodine, calcium, potassium, iron, carotene, mannitol (a natural sugar), protein, niacin, phosphorus, vitamin C, B-complex and many others). It has and can be used in recipes such as dashi, a Japanese soup stock.  The stems are also used in medical practice acting as ‘bougies’ – small cylindrical tubes used to probe body passages for both diagnosis and treatment. They can be dried and kept safely for years, returning to their elastic state when moistened.

Oarweed is also used in balneotherapy (sea baths used for medicinal purposes) and in therapeutic products for spas, either on its own or dried and combined with the calcareous Lithothamnions to create skin cleanser exfoliants.  Working through the skin, these are used to combat muscular aches and pains, increase circulation, detoxify the skin, break down cellulite thus increasing the skin’s firmness and elasticity.

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