Knotted wrack is a ubiquitous seaweed that thrives along shallow rocky shores of Scotland’s coastline and in her sea lochs. Cascading in great green-brown tresses from the midlittoral zone, it hones in on the southwest facings of rocks and banks to establish colonies, leaving its zonal neighbour, Fucus vesiculosus (Bladderwrack) to populate the darker sides.
Pockets of air fill its multitudinous nodes allowing it to reach the warmer, sunlit waters of the higher tide; its pale yellow tips inches below the surface at the water’s height, or lying in great blankets across the surface at mid-height. At low tide, its thick kelp-like stems and branches, with their reserves of natural oils and moisture, wrap around themselves, to keep safe at from sun, rain and wind.
Prolific it may be, but not alone – it also shelters the little Polysiphonia lanosa (aka Vertebrata lanosa) who latches on to the Ascophyllum’s stems, capitalising on the larger seaweed’s position, and helping to protect it against the threatening elements of the lowest tides.
In Scotland, knotted wrack has traditionally been used for fertiliser – harvested or collected by horse and cart in autumn, spread on fields to release its nitrogen and magnesium throughout the winter and then plowed under in spring. Many coastal towns have a ‘Ware’ road – testament to this ancient activity. Our own was used by the Cistercian nuns of North Berwick Abbey whose fields bordered its sides and who used it to grow acres of potatoes leeks, cabbages, oats and barley for their community and wider trade.
Rich in natural minerals (including nitrogen, phosphorus, selenium, zinc, magnesium, potassium and iron), Ascophyllum is also harvested in Italy where is noted for its therapeutic value in thassolopathy and used to make eye-sprays (an alternative to eye-bright). In France it is used in an increasing range of anti-aging and anti-inflammatory beauty products and recent research conducted in Iceland and Britain has highlighted its usefulness in treating thyroid conditions, post cancer patients, and for exhausted skin conditions such as eczema and psoriasis.