Jamaican Irish moss (Chondrus crispus) is a very common, and commercially important weed in Jamaica. It is also cultivated in Atlantic Canada. Also known as Carrageen or Pearl Moss, this seaweed also grows among submerged rocks off the coast of France and, naturally, Ireland. The plant consists of a greenish frond that turns purple when dried. The Irish consumed Jamaican Irish moss during the famine of the 19th century.