Marine Wildlife Encyclopedia
Laver Porphyra dioica
This species of red seaweed has only recently been separated from the very similar P. purpurea on the basis of how they reproduce. P. dioica is dioecious (male and female reproductive cells are on separate fronds), while P. purpurea is monoecious (male and female reproductive cells are on the same frond). P. dioica grows on intertidal, sandy rocks and is most abundant in the spring and early summer. The membranous frond is only one cell thick and is olive-green to purple-brown or blackish. This species appears to have a limited distribution in western Europe, but the genus is widespread throughout the world. All species of Porphyra are edible and are often harvested for food worldwide, especially in Japan where they are cultivated and known as nori. In the United Kingdom, wild laver is collected and made into the Welsh delicacy laverbread.