148
WILLIAM MACNAE
whole fruit drops. I n B. parviJora the plumule breaks through the base
of the fruit and the fruit, collar-like, encircles the junction of plumule
and radicle (Fig. 42, 3). Growth continues as soon as the seedling is
grounded. Most do not germinate in the mud beneath the parent tree
but may float for some time before settling.
In Aegiceras corniculatum (Fig. 42, 5a,b,c), quoting from van
Steenis (in Ding Hou, 1958), " the embryo ruptures the testa and fills
the pericarp which then starts to enlarge in proportion to the growth of
the embryo ; after the enlarged fruit has fallen the embryo pierces the
pericarp ".
I n Avicennia spp. (Fig. 42, 4) there is a similar development and
when the fruit drops it seems to absorb water and then splits and the
seedling breaks out of the pericarp.
No description has been given of seedling development of Lumnitxera
spp. I n Xylocarpus the fruit is very large (Figs. 43 and 44) ; that of
X . granatum reaches the size of a baby's head, and that of X . moluccense
of a cricket ball. These fruits drop, float around, become grounded, rot,
split and liberate the seeds which are by now ready to germinate. The
time interval is unknown.
Again nothing has been reported on the germination methods of
such opportunist species as the beach thistles, Acanthus ilicifolius.
I n development the ferns Acrostichum aureum and A . speciosum
are normal. Spores of the former germinate in the landward fringe on
bare soil or on cast up jetsam brought in by the tide. Spores of the
latter behave differently. As has been mentioned above, this species is
common in the bruguiera forests. On the floor of these forests Thalassina
anomala casts up its mounds, the upper parts of which rise above the
levels reached by all but extreme tides. On these higher parts of the
mounds the surface dries out a little, becomes bound by blue-green
algae and in these algal mats the fern spores germinate, and so a field
layer is produced and the general soil level gradually raised by the ferns.
E . Xuccession
Of the trees and herbaceous plants constituting a mangrove the
following species seem to prefer t o germinate and become established
in full sunlight or at most in only slight shade :
"Acanthus ilicifolius
Ceriops decandra
"Xonneratia alba
Aegialitis annulata
Lurnnitzera racemosa
"apetala
"Avicennia alba
Rhizaphora stylosa
"grifithii
"marina
mucronata
Aegiceras corniculatum
apiculata
WILLIAM MACNAE
whole fruit drops. I n B. parviJora the plumule breaks through the base
of the fruit and the fruit, collar-like, encircles the junction of plumule
and radicle (Fig. 42, 3). Growth continues as soon as the seedling is
grounded. Most do not germinate in the mud beneath the parent tree
but may float for some time before settling.
In Aegiceras corniculatum (Fig. 42, 5a,b,c), quoting from van
Steenis (in Ding Hou, 1958), " the embryo ruptures the testa and fills
the pericarp which then starts to enlarge in proportion to the growth of
the embryo ; after the enlarged fruit has fallen the embryo pierces the
pericarp ".
I n Avicennia spp. (Fig. 42, 4) there is a similar development and
when the fruit drops it seems to absorb water and then splits and the
seedling breaks out of the pericarp.
No description has been given of seedling development of Lumnitxera
spp. I n Xylocarpus the fruit is very large (Figs. 43 and 44) ; that of
X . granatum reaches the size of a baby's head, and that of X . moluccense
of a cricket ball. These fruits drop, float around, become grounded, rot,
split and liberate the seeds which are by now ready to germinate. The
time interval is unknown.
Again nothing has been reported on the germination methods of
such opportunist species as the beach thistles, Acanthus ilicifolius.
I n development the ferns Acrostichum aureum and A . speciosum
are normal. Spores of the former germinate in the landward fringe on
bare soil or on cast up jetsam brought in by the tide. Spores of the
latter behave differently. As has been mentioned above, this species is
common in the bruguiera forests. On the floor of these forests Thalassina
anomala casts up its mounds, the upper parts of which rise above the
levels reached by all but extreme tides. On these higher parts of the
mounds the surface dries out a little, becomes bound by blue-green
algae and in these algal mats the fern spores germinate, and so a field
layer is produced and the general soil level gradually raised by the ferns.
E . Xuccession
Of the trees and herbaceous plants constituting a mangrove the
following species seem to prefer t o germinate and become established
in full sunlight or at most in only slight shade :
"Acanthus ilicifolius
Ceriops decandra
"Xonneratia alba
Aegialitis annulata
Lurnnitzera racemosa
"apetala
"Avicennia alba
Rhizaphora stylosa
"grifithii
"marina
mucronata
Aegiceras corniculatum
apiculata