Agar-producing seaweeds grow naturally around the 25th parallel of longitude, on rocks in the littoral region (just below low-tide level) round the coasts of Japan, Spain, Portugal, Morocco, Senegal, the southern United States, Mexico, Chile, India, the Philippines and Madagascar. The most important sources of agar-agar are the seaweeds with a cylindrical stalk at the base which open out into fronds about 2 mm thick. They are attached to the rocks with a network of roots. |