Palmaria palmata

Lore & Background

Palmaria palmata has a long history of human use, with 5th century laws of archaic Ireland concerning the eating of duileasc. The erect frond grows attached by a discoid holdfast and short stipe, epiphytically on Laminaria or rocks. The fronds are variable in shape and colour from deep rose to reddish purple, leathery in texture, and can reach 50 cm in length. The blade consists of an outer cortex of small cells enclosing a medulla of larger cells.

The full haplodiploid life history was not fully explained until 1980. There are two phases: a haploid phase that is dioecious, with separate male and female plants. The large haploid male plants produce spermatia that fertilize the carpogonia of the minute female crust (less than 1 mm). After fertilization, the resulting diploid plant overgrows the female. The adult tetrasporophyte produces tetraspores meiotically in fours.

Ecologically, P. palmata grows from mid-tide of the intertidal zone to depths of 20 m or more on sheltered and exposed shores. It is commonly found from June to September and can be picked by hand at low tide. Galls, possibly produced by parasitic nematodes, copepods, or bacteria, are known to infect these plants.

Reader's Guide

Palmaria palmata holds significance as a traditional food source in Ireland, Iceland, and Atlantic Canada, where it is commonly used as food and medicine. It is a good source of minerals and vitamins, contains all trace elements needed by humans, has a high protein content, and contains iodine, which prevents goitre. In Iceland, the tradition is to eat it with butter. In Ireland, it is used to make White Soda Bread and is traditionally sold at the Ould Lammas Fair in Ballycastle, Northern Ireland. Along the Ulster coastline, it is eaten dried and uncooked as a snack. Dulse can be pan-fried into chips, baked with cheese, used in soups, chowders, sandwiches, salads, or added to bread or pizza dough. Finely diced, it can replace monosodium glutamate as a flavour enhancer in meat dishes. Researchers at Oregon State University's Hatfield Marine Science Center have selected a fast-growing strain of Pacific dulse (P. mollis) that they claim tastes like bacon when fried. The species is the only Palmaria found on the coast of Atlantic Europe, ranging from Portugal to the Baltic coasts, Iceland, the Faroe Islands, Arctic Russia, Arctic Canada, Atlantic Canada, Alaska, Japan, and Korea.

Did You Know?

• 5th century laws of archaic Ireland existed concerning eating duileasc.
• The full haplodiploid life history of Palmaria palmata was not fully explained until 1980.
• In Iceland, it is known as söl and has been an important source of dietary fibre throughout the centuries.
• Researchers at Oregon State University's Hatfield Marine Science Center claim a fast-growing strain of Pacific dulse tastes like bacon when fried.