| Gigartina, Gigartinales, Himanthalia elongata, Fucus spiralis, Irish Moss|
Mastocarpus stellatus, also called Clúimhín Cait (cats' puff), carragheen, or false Irish moss, is a species of red algae closely related to Irish Moss, or Chondrus crispus. It is collected in Ireland and Scotland, together with Chondrus crispus as Irish moss, dried, and sold for cooking and as the basis for a drink reputed to ward off colds and flu.
It grows from a discoid holdfast stipe, the fronds are channelled unlike those of Chondrus crispus which are flat. It grows to a height of 10 to 20 cm and branches dichotomously. The mature algae show reproductive structures which develop on erect filaments up to 1 mm in diameter, these make it readily distinguishable from Chondrus crispus. In colour it is reddish brown, purple or bleached.
It occurs commonly on rocks in the mid- and lower-intertidal.
Mastocarpus stellatus is able to coexist with C. crispus on the northern New England coast despite being a competitive inferior to C. crispus. A greater tolerance for freezing allows it to exist above C. crispus in northern environments where freezing stresses are significant. Mastocarpus is rarely found south of Cape Cod on the United States Atlantic coast because it is out competed by Chondrus when the freezing tolerances are lower.
Generally common on all coasts of Ireland and Britain, except perhaps for parts of the east of England - Lincoln, Norfolk and Suffolk. Also recorded from: Iceland, Faeroes, North Russia to Rio de Oro, Canada (Newfoundland) to U.S.A (North Carolina).
Mastocarpus stellatus Wikipedia