Irish Moss is the common name for a red algae (Chondrus crispus), but may also refer to 1 or 2 other red seaweeds (Gigartina stellata and Furcellaria lumbricalis). C. crispus, the only species of the genus in the Atlantic Ocean, occurs from New Jersey to Labrador, and is most abundant in NS and the lower Gulf of St Lawrence. The plants are perennial, grow on rock in lower tidal and subtidal zones, and arise from disclike "holdfasts." Commonly, the fronds are up to 15 cm high, branched (usually in one plane only) and fan-shaped. The colour varies (dark red, purple, yellow-green), depending on physiological conditions. Dried plants are nearly black. A life cycle consisting of 2 independent and structurally similar phases (sexual and asexual) has been demonstrated in the laboratory.
Irish moss is Canada's most valuable commercial seaweed. Originally used in blancmanges and milk jellies, it is still available in "natural food" stores. The dried plants are used to clarify beers, wines, coffee and honey. Since WWII, major exploitation has been for extraction of hydrocolloids (substances yielding gel when water is added, eg, carrageenians) used in convenience foods. Carrageenan is not processed in Canada, and thousands of tonnes of Irish moss are exported annually. Aquaculture trials, in tanks and pools, have been carried out in NS.