138
A. D. BONEY
weight of proliferation on young plants could be as much as to loosen
the holdfast, and so cause loss of the plants. Two harvests a year are
carried out on the French coast. I n experiments on the Isle of Man
where fronds of F . vesicub8w were cut to 30 cm and 15 cm from the
base, plants with fronds cut 30 cm from the base had a similar fresh
weight after 13 months regrowth to that of uncut control plants,
whereas those cut to within 15 cm from the base equalled about half
the fresh weight over the same time interval.
Culture studies on regenerative growth of Fucus vesiculosus have
been described by Moss (1964a,b). At any time of the year the apicaI
segments of young thalli show a more rapid growth rate. The relative
failure of cut ends of the thalli to regenerate a new apical meristem is
an indication of the apical dominance phenomenon. Other parts of the
plant which lacked a functional meristem prior to their introduction
into culture solution produced new branches, each bearing an apical
meristem. I n practice, new branches are produced in greater numbers
from the middle regions of young thalli, and in much smaller numbers
from older plants. The more marked regenerative growth is observed
during April and May, and indicates a seasonal pattern of regenerative
growth. Such a feature will be important in re-growth of plants after
harvesting. Fucus serratus plants do not show the marked degree of
proliferation demonstrated by F . vesicubsus, but the results of experiments in which regrowth was measured after various degrees of frond
truncation showed a similar trend to those described above. Repopulation of cleared areas after 3 years showed an almost complete
recuperation of the standing-crop. Knight and Parke (1950) suggested
that cropping of F . vesiculosus and F. serratus every 2 years would give
the best results. This strikes an even balance between young 1st-year
plants which are not large enough and 3rd-year plants in which the
frondage is large, but the rate of depopulation due to natural causes
is steadily rising. Since the plants are at their maximum vigour in spring
prior to the onset of fruiting this would appear to be the best time for
harvesting, and certainly before the controlled defoliation which
follows fruiting although it would be important to leave some fertile
branches to allow repopulation by sporelings. Removal of fronds can
be of advantage in encouraging the growth of young plants and sporelings which would be shaded or crowded out by the dense cover of
older plants.
In more recent years a considerable amount of work has been carried
out on the taxonomic relationships between Fucus species (Burrows
and Lodge, 1951; Powell, 1957a,b; 1963; Evans, 1962) and a more
detailed knowledge of the specific limits is now available. Burrows and
A. D. BONEY
weight of proliferation on young plants could be as much as to loosen
the holdfast, and so cause loss of the plants. Two harvests a year are
carried out on the French coast. I n experiments on the Isle of Man
where fronds of F . vesicub8w were cut to 30 cm and 15 cm from the
base, plants with fronds cut 30 cm from the base had a similar fresh
weight after 13 months regrowth to that of uncut control plants,
whereas those cut to within 15 cm from the base equalled about half
the fresh weight over the same time interval.
Culture studies on regenerative growth of Fucus vesiculosus have
been described by Moss (1964a,b). At any time of the year the apicaI
segments of young thalli show a more rapid growth rate. The relative
failure of cut ends of the thalli to regenerate a new apical meristem is
an indication of the apical dominance phenomenon. Other parts of the
plant which lacked a functional meristem prior to their introduction
into culture solution produced new branches, each bearing an apical
meristem. I n practice, new branches are produced in greater numbers
from the middle regions of young thalli, and in much smaller numbers
from older plants. The more marked regenerative growth is observed
during April and May, and indicates a seasonal pattern of regenerative
growth. Such a feature will be important in re-growth of plants after
harvesting. Fucus serratus plants do not show the marked degree of
proliferation demonstrated by F . vesicubsus, but the results of experiments in which regrowth was measured after various degrees of frond
truncation showed a similar trend to those described above. Repopulation of cleared areas after 3 years showed an almost complete
recuperation of the standing-crop. Knight and Parke (1950) suggested
that cropping of F . vesiculosus and F. serratus every 2 years would give
the best results. This strikes an even balance between young 1st-year
plants which are not large enough and 3rd-year plants in which the
frondage is large, but the rate of depopulation due to natural causes
is steadily rising. Since the plants are at their maximum vigour in spring
prior to the onset of fruiting this would appear to be the best time for
harvesting, and certainly before the controlled defoliation which
follows fruiting although it would be important to leave some fertile
branches to allow repopulation by sporelings. Removal of fronds can
be of advantage in encouraging the growth of young plants and sporelings which would be shaded or crowded out by the dense cover of
older plants.
In more recent years a considerable amount of work has been carried
out on the taxonomic relationships between Fucus species (Burrows
and Lodge, 1951; Powell, 1957a,b; 1963; Evans, 1962) and a more
detailed knowledge of the specific limits is now available. Burrows and