BIOLOQY OF SEAWEEDS OF EOONOMIO IMPORTANOE
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17. Ahnfeltia
Ahnfeltia plicata is characterized by the possession of a tough wiry
thallus with dichotomous branching. The erect branches grow from a
discoid attaching system consisting of small cells, and the structural
features of the slender branches include a medulla of elongate and thickwalled cells, with radiating filaments of smaller cells forming the cortex.
Annual growth rings are formed by the division of outer cells of the
cortex. The plant is relatively slow-growing, and is found in rock pools
in the region of low water mark, and somewhat larger plants are found
in sublittoral habitats. Spore production is by way of specialized
structures, the nemathecia, which are yellowish-white in appearance.
These arise by the increased cell division of certain areas of the cortex,
and the threads of cells so formed terminate in monosporangia. The
problematical nature of these structures has engaged much attention,
together with the absence of any female organs in the species. Ahnfeltia
has some limited usage as a source of extractives, and more detailed
studies on its productivity and maintenance would be valuable,
particularly as it appears to be rather slow-growing.
18. Phyllophora
Reference has already been made to the Phyllophra beds of the
Black Sea (p. 125) and to the three species concerned, Phylbphora
nervosa, P. brodiaei and P . membranifolia. The standing crop consists
of free-living plants, and is apparently maintained by vegetative growth.
The attached forms of the species are small, dichotomously branched
and foliose in appearance, with discoid holdfasts. Plants are perennial,
and new pale-coloured frondage is observed each year. The attached
plants are characterized by proliferative marginal growth, and this
indicates the source of new frondage in the free-living forms. Structurally the plants are characterized by a medulla of thick-walled cells
and a cortex of radiating filaments. The life-histories of the genera are
of a, specialized, reduced nature.
19. Gloiopeltis
The cylindrical thalli of Gloiopeltis are found on Pacific shores, and
seem well able to withstand desiccation effects in the intertidal zones.
The plants are particularly valued in Japan as sources of glue (" funori ")
and studies on the biology of two species have been reported, Gloiopeltis
furcata and G. tenax.
According to Fukuhara (1966) Gloiopeltis furcata tends to dominate
the shore zone it inhabits throughout the year. Young plants appear in
late summer and early autumn, and the best time for harvesting is the
199
17. Ahnfeltia
Ahnfeltia plicata is characterized by the possession of a tough wiry
thallus with dichotomous branching. The erect branches grow from a
discoid attaching system consisting of small cells, and the structural
features of the slender branches include a medulla of elongate and thickwalled cells, with radiating filaments of smaller cells forming the cortex.
Annual growth rings are formed by the division of outer cells of the
cortex. The plant is relatively slow-growing, and is found in rock pools
in the region of low water mark, and somewhat larger plants are found
in sublittoral habitats. Spore production is by way of specialized
structures, the nemathecia, which are yellowish-white in appearance.
These arise by the increased cell division of certain areas of the cortex,
and the threads of cells so formed terminate in monosporangia. The
problematical nature of these structures has engaged much attention,
together with the absence of any female organs in the species. Ahnfeltia
has some limited usage as a source of extractives, and more detailed
studies on its productivity and maintenance would be valuable,
particularly as it appears to be rather slow-growing.
18. Phyllophora
Reference has already been made to the Phyllophra beds of the
Black Sea (p. 125) and to the three species concerned, Phylbphora
nervosa, P. brodiaei and P . membranifolia. The standing crop consists
of free-living plants, and is apparently maintained by vegetative growth.
The attached forms of the species are small, dichotomously branched
and foliose in appearance, with discoid holdfasts. Plants are perennial,
and new pale-coloured frondage is observed each year. The attached
plants are characterized by proliferative marginal growth, and this
indicates the source of new frondage in the free-living forms. Structurally the plants are characterized by a medulla of thick-walled cells
and a cortex of radiating filaments. The life-histories of the genera are
of a, specialized, reduced nature.
19. Gloiopeltis
The cylindrical thalli of Gloiopeltis are found on Pacific shores, and
seem well able to withstand desiccation effects in the intertidal zones.
The plants are particularly valued in Japan as sources of glue (" funori ")
and studies on the biology of two species have been reported, Gloiopeltis
furcata and G. tenax.
According to Fukuhara (1966) Gloiopeltis furcata tends to dominate
the shore zone it inhabits throughout the year. Young plants appear in
late summer and early autumn, and the best time for harvesting is the