Chondrus crispus Stackhouse
Common names: Irish Moss, Carragheen, Carrageen, Carrageen Moss (Eng.), Mousse d'Irlande (French), Irisch Moos (German), Carraigín (Irish)
Description: Cartilaginous, dark purplish-red fronds, female plants sometimes iridescent at the apices under water when in good condition (below) and turning almost completely greenish-yellow in upper-shore rock-pools (below), to 150 mm high. Stipe compressed, narrow, expanding gradually onto a flat, repeatedly dichotomously branched blade, in tufts from a discoid holdfast. Axils rounded, apices blunt or subacute, frond thicker in centre than margins. Very variable in breadth of segments (see broad form below).
Habitat: On rocks (above), in pools, lower intertidal and shallow subtidal, widely distributed, abundant.
Usage: A source of carrageenan (a sulphated polysaccharide), and used to make soups, jellies, etc., and in Ireland as a remedy for respiratory disorders (colds, influenza and tuberculosis). The colloquial English name "Carrageen" was introduced in Ireland about 1840 by a Mr Todhunter from Donegal and is likely to have been taken from Carrigeen (or Carrigan) Head in Co. Donegal and not from a town or townland name in Co. Waterford; however, Carrageen or Carrigeen (carraigín, Irish: diminutive of rock) is an exceedingly common placename in Ireland. Chondrus crispus plants gathered in the shallow subtidal of some of the Maritime Provinces of Canada is an important source of the industrially-important hydrocolloid carrageenan.
Similar species: Mastocarpus stellatus is frequently collected with Chondrus crispus and sold as a mixture under the name Carrageen or Irish Moss.
Note: in Germany there is currently a line of personal toiletries known as Irisch Moos.
Photographs © M.D. Guiry