176
A. D. BONEY
have mainly a restricted area of sale in Wales and south-west England,
the plants are harvested on the coast of Wales, and from the shores of
Scotland, Ireland, Cornwall and north England. More than 50% of the
Porphyra sold in 1954 came from shores in Scotland (Hampson, 1957).
Of the three species, P . umbiZicaZis in particular is found throughout
the year on shores exposed to severe wave action in Scotland, whereas
P . purpurea is found from early spring onwards and tends to disappear
during the storms of late winter (Conway, 1964a). Whilst the plants
can be collected all the year round, there is a fall in demand during the
summer months. The time of maximum sale of the " laverbread " is
in fact the period of much slower growth by the plants, and when a
reduction of the standing crops results from the action of gales and
heavy seas. The Porphyra harvesters work a type of rotation on the
shores or on regions of the shore, and the best plants are found hanging
from the underside of boulders with the free ends immersed in water.
Prolific growths are observed where fresh water runs into the sea and
lowers the salinity of the sea water, but this may also be due to increased
nutrients brought down by land drainage.
6. Species of Porphyra utilized in the United States
The principal species utilized as food on the Pacific coast of the
United States is Porphyra perforata. Here the lanceolate fronds can
attain a length of 5 ft, but are usually harvested when 2 to 3 f t long
(Tseng, 1947). On shores where the laver grows the rocks are burned
with driftwood in the fall, so clearing the substratum of other plants
and leiding to an enhanced growth of the Porphyra plants the following
spring. When Hollenberg (1958) germinated the " carpospores " of
this species on glass slides he obtained filamentous plants which might
well be the form of plant occurring in nature, since the shell-boring
phase of this species does not occur on the California coast of the United
States. I n experiments carried out with the filaments under conditions
of culture these filaments developed sporangia, and the spores produced
young Porphyra plants on germination. Whilst the shell-boring phase
is not known on the coast of California, it has been reported from the
Washington coast (Jao, 1937).
Porphyra species utilized in other parts of the world include P.
suborbiculata which is collected from the shores of Hong Kong during
December, January and February, (Chiu, 1958), and in the Philippines
a Porphyra species was under test as a source of feeding stuff (Sulit
et al., 1953).
A. D. BONEY
have mainly a restricted area of sale in Wales and south-west England,
the plants are harvested on the coast of Wales, and from the shores of
Scotland, Ireland, Cornwall and north England. More than 50% of the
Porphyra sold in 1954 came from shores in Scotland (Hampson, 1957).
Of the three species, P . umbiZicaZis in particular is found throughout
the year on shores exposed to severe wave action in Scotland, whereas
P . purpurea is found from early spring onwards and tends to disappear
during the storms of late winter (Conway, 1964a). Whilst the plants
can be collected all the year round, there is a fall in demand during the
summer months. The time of maximum sale of the " laverbread " is
in fact the period of much slower growth by the plants, and when a
reduction of the standing crops results from the action of gales and
heavy seas. The Porphyra harvesters work a type of rotation on the
shores or on regions of the shore, and the best plants are found hanging
from the underside of boulders with the free ends immersed in water.
Prolific growths are observed where fresh water runs into the sea and
lowers the salinity of the sea water, but this may also be due to increased
nutrients brought down by land drainage.
6. Species of Porphyra utilized in the United States
The principal species utilized as food on the Pacific coast of the
United States is Porphyra perforata. Here the lanceolate fronds can
attain a length of 5 ft, but are usually harvested when 2 to 3 f t long
(Tseng, 1947). On shores where the laver grows the rocks are burned
with driftwood in the fall, so clearing the substratum of other plants
and leiding to an enhanced growth of the Porphyra plants the following
spring. When Hollenberg (1958) germinated the " carpospores " of
this species on glass slides he obtained filamentous plants which might
well be the form of plant occurring in nature, since the shell-boring
phase of this species does not occur on the California coast of the United
States. I n experiments carried out with the filaments under conditions
of culture these filaments developed sporangia, and the spores produced
young Porphyra plants on germination. Whilst the shell-boring phase
is not known on the coast of California, it has been reported from the
Washington coast (Jao, 1937).
Porphyra species utilized in other parts of the world include P.
suborbiculata which is collected from the shores of Hong Kong during
December, January and February, (Chiu, 1958), and in the Philippines
a Porphyra species was under test as a source of feeding stuff (Sulit
et al., 1953).