Cultivating Palmaria palmata - Bord Iascaigh Mhara

After release, these tetraspores settle onto a substrate and develop into male and female gametophytes in a 1:1
ratio. This gametophyte part of the life cycle is very unusual among algae in that males and females are
completely different in morphology and life span. At an immature stage (i.e. before reproduction begins after
about 1 year), the male gametophytes are indistinguishable from the diploid tetrasporophytes. In contrast, the
female gametophytes develop into microscopic crustose thalli, no more than 3-4 cells thick and 0.1 mm in
diameter (Fig. 2.3 c-e). Consequently, female gametophytes cannot be detected on the shore and they were only
discovered relatively recently through culture studies (van der Meer & Chen, 1979; van der Meer & Todd, 1980).
If their egg cells (carpogonia) are not fertilised within a few days, the female gametophytes die. Since the male
gametophytes of the same generation are all immature at this stage, the females must be fertilised by gametes
from males released in the previous year, and this ensures a good mixing of genetic material. After fertilisation, a
zygote is formed and a new tetrasporophyte develops on top of the female gametophyte, and soon overgrows it
(Fig. 2.3 f).
The male gametophyte reaches sexual maturity 9-12 months after germination. Spermatangial sori are formed
that release spermatia which fertilise the egg cells of female gametophytes. The sori resemble the sori of the
tetrasporophyte in shape but have a milky to translucent appearance.
Tetrasporophytes become fertile during winter. This coincides with the reproductive time of male gametophytes
from the previous year. The reproductive season starts in November-December at most sites around Ireland and
lasts until March/April.
2.5 Uses and nutritional value of Palmaria palmata
Palmaria palmata has a long history of use as a sea vegetable. The earliest record of the collection of Palmaria
for food in Ireland is found in a poem written by an Irish monk in the 12 th century. It is also mentioned in Icelandic
sagas from the 11 th century onwards but was used also in other countries such as Norway and France and on
the east coast of Canada. Descriptions of Palmaria as a herbal remedy against, for example, worm infestation
can be found in some European herbal books of the 18 th century (www.algaebase.org).
In Ireland, England and Scotland, Palmaria is known under the name Dulse or Dillisk. In Gaelic, there are two
names to describe Palmaria: Creathnach (feminine) and Duileasc (masculine). The first describes a smaller,
narrower form that generally grows on small mussels on more exposed shores, also called “Shell-dulse”. The
masculine form Duilleasc is used for the more commonly distributed larger, broader form that grows directly on
kelp, Fucus or rocks (www.algaebase.org).
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