Mower County transcript. [volume] (Lansing, Minn.) 1868-1915, 1888-07-04
REMARKABLE TREES.
Tho Part Played by the Mangrove in
Forming the Florida Peninsula.


Forming the Florida Peninsula.
Among the agencies that have helped
to build up the peninsula of Florida
may be numbered certain trees which
are fitted by nature to grow on lands
that are more or less under water, and
that are too unsubstantial to support
other forms of vegetation. Like the
coral builders, they work so slowly
that in single century no great
change is accomplished, but in thou
sands OF centuries the changes wrought
| are very great. The most important
OF these tree-workers are the mangrove
and the cypress. The former grows
| on shores and shoals that are overAown
generally by salt tide-water; the latter
in localities that are overfowed at
times by fresh water. Both have
similar obstacles to overcome, and they
accomplish this by very different means.
The red mangrove (Rhizophora
Aomgle) covers hundreds of square
| miles of the southern shores of Flori-
da, the principal areas occupied by it
being the shoals lying between the
keys and the mainland-which are
composed of calcareous sediment
| the low southern and western borders
of the everglades. In these localities,
| and on tide-washed islands as far north
as latitude 20 deg, it forms a dense
thicket of vivid green, rising uniform
~ from high-water level, unchanged
by seasons, unaffected by hurricanes,
lnsidiously encroaching on the domain
OF waters and helping build what in
future ages will be dry land. Far in
the interior, even on the northern
border of the State, are found beds of
calcereous sedimentary rock which
may once have supported just such
thickets of mangrove.
In places on the mainland shores the
mangrove attains to tree-like dimen-
sions, forming tall trunk sometimes
two feet in diameter. Like the cy-
press, the mangrove is provided with
strong buttresses at the base, but these
differ from those of the cypress in be-
ing of the style called by architects
''fying' buttresses. Starting from the
trunk yard or two from it's base, they
descend in graceful curves, sending off
branches, from which other branches
proceed, all descending in similar
curves to the muddy ground, over
which the tides spread twice day.
These basal branches serve the double
purpose of props and feeders. From
the upper branches aerial roots de-
scend till they reach the water at high
tide. Sometimes a tree may be seen
entirely dead except as to one branch,
which is kept green by sucking up
| water through an aerial root perhaps
twenty feet long.
Another special provision for its en-
vironment is seen in the seed of the
mangrove. This, before falling from
the branch, develops into a miniature
trunk from six to twelve inches long.
The basal end being the heaviest, is
most likely to strike the muddy surface
first and to stick there in an erect po-
sltiOn. The rOotlets and seed-leaves
being ready to push forth, the young
plant makes a rapid growth and soon
becomes well-rooted and propped in it's
rather insecure position.
| AS the mangrove usually grows, ris-
ing scarcely ten feet from the water
and spreading laterally, the main stem
is OF little Importance. Innumerable
roots descend from and support the
leafy branches, repeatedly forking in
their descent and forming sort of
basket work below high-water level.
Floating objects become lodged in these
natural weirs, shell-fsh and other
marine creatures multiply in them,
and the submerged stems give support
to seaweeds and hydroids. In some
localities the roots become encased
with oyster shells, and this, probably,
is the origin of many of the oyster bars
that obstruct some of the lagoons or
so-called rivers of Southern Florida.
The mangrove thickets in the course
of time build up foundation for other
species. OF these none have peculiar
habit of growth, except the black man
grove (Avicen'aia aaitida). This tree is
remarkable as to foliage, fruit, wood,
bark and roots. The surface roots
send upward innumerable short feed
ers, black, 1.-the and rising about q
span above the surface. This function.
evidently, is to draw nutriment from
the water at high tide, and, like
the knees of the cypress, they add
to the surface accommodations, which,
from age to age, add to the elevation
of the land. In this respect, however,
neither of these trees equals the red
mangrove.
The wood of the red mangrove sinks
in water and is not attacked by marine
worms. Hence, fallen branches and
trunks remain where they fall, while
material that floats in with the tide is
detained by the network of basal
branches. 1t is altogether probable
that the thousands of tree-covered
''islands" in the everglades and big
cypress were once mangrove thickets
! and that the present manprOve islands