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MANGROVES.
Rhizcphon.

TJie Mangrove and its Allies. 65

THE MANGROVE AND ITS ALLIES.

BY JOHN R. JACKSON,

Curator of the Museum, Eoyal Gardens, Zew.

(With a Tinted Plate.}

THE peculiar manner of growth of the Banyan, and other allied
species of Ficns, we noticed in a recent number of the INTEL-
LECTUAL OBSERVER. In the Moracece, it will be recollected that
the habit of increasing the circumference of the plants, is by the
downward growing branches, which strike root upon meeting
the ground. In the Wiizopliora, another singular, though
very distinct mode of growth occurs, and of this the Mangrove
is a well-known example. Most of our readers are aware of
the existence of such a plant ; but some of them may, perhaps,
not be so intimately acquainted with it as to understand clearly
its mode of germination ; nor are they, perhaps, aware that there
is more than one species of Rhizophora, having the same
peculiarity.

The name of Mangrove is associated in our minds with very
unfavourable ideas of locality, we have read of Mangrove
swamps, and we have notions of stagnant or muddy shores,
fostering malaria or disease. We most of us know so much of
its habitat ; but we will endeavour to explain to our readers a
little more about the Mangrove and its allies.

The genus Rhizophora, then, gives the title to a distinct
natural order called Rhizophoracece, and placed according to the
latest authority, Hooker and Bentham's Genera Plantarum,
between Haloragece and Combretacece. The order is divided
into three tribes : Rhizophorce, Legnotidce, and Anisophyllce,
numbering in all seventeen genera, and the four comprising
the tribe Rhizophorce, have a similar habit of germinating their
seeds before leaving the parent, these four genera are Rhizo-
phora, Ceriops, Kandelia, and Brugueira.

The order is entirely a tropical one, and consists of trees or
shrubs, mostly inhabiting the sea shore. The leaves are oppo-
site, and the flowers usually axillary, the lobes of the calyx are
valvate, not imbricate, the stamens arise from the same point
as the petals, and are twice or three times their number,
though in Kandelia they are indefinite. The ovary or fruit
is sometimes superior, or seated above the calyx, as in Rhizo-
phora, the calyx is persistent in several of the species.

The genus Rhizophora is distinguished from its allies, by

the calyx being divided into four parts, the four petals sharply

pointed, and the stamens which are from eight to twelve in

number, having short filaments, and anthers with little pits,

VOL. xi. — NO. i. 3o0267 F

66 The Mangrove and its Allies.

containing the pollen. The ovary is partially adherent, and
contains two cavities in the part where it so adheres, each of
these cavities bearing two ovules ; the free part tapers towards
the top into a single style.

The Mangrove, Bhizophora Mangle, L., is an evergreen tree,
rising some forty or fifty feet high, and presenting a very
singular appearance, both as regards the appendages of its
branches, and its peculiar manner of rooting. The following
description of the Mangrove, is from a paper, read before the
Pharmaceutical Society, by Dr. Hamilton, in June, 1846. —
" The Mangrove is a tree frequently of imposing stature, attain-
ing an altitude of from thirty to fifty feet or more, and occupy-
ing marshy situations, in the vicinity of the sea, as at the
bottom of English Harbour, Antigua, and near the mouth of
the little river which empties itself into the harbour, at Cape
Henri, Hayti. Its roots rise in the form of arches, above
the muddy soil in which it grows, and affords attachment to
myriads of small but delicious oysters, which are left bare
during the efflux of the tide, giving rise to the popular fable
of oysters growing on trees, which, with the exception of their
not being fed by, but merely adhering to the tree, is literally
true. These oysters make a most incomparable soup, of which
I once partook at the house of an American merchant, at Cape
Henri.

" The shade of these trees affords harbour during the day
to innumerable swarms of mosquitoes, which nestle on the
under surface of the leaves, and infest the houses of those who
have the misfortune to live in the vicinity of a Mangrove
swamp during the night.

" But in the economy of nature, the Mangrove performs a
most important part, wresting annually fresh portions of the
land from the dominion of the ocean, and adding them to the
domain of man ; this is effected in a two-fold manner, by the
progressive advance of the roots, and by the aerial germination
of the seeds, which do not quit their lofty cradle, till they
have assumed the form of actual trees, and drop into the
water with their roots ready prepared to take possession of the
mud in advance of their parent stems, and repel to a further
and perpetually increasing distance the invasion of the water.
The progression by means of the roots is effected by fresh
roots, which issue from the trunks, at some distance above the
surface of the water, and arching downwards, penetrate the
mud, establishing themselves as the pioneers of fresh invasions
of the retiring element. In this manner the plants soon after
their descent from their parent trees, continue, during their
early years, to advance steadily forward till they have attained
a height of about fifteen feet, and considerably in advance of

The Mangrove and its Allies. 67

their parent trunks. After this, fewer additions are made to
the roots, but the head begins to expand in every direction,
spreading its branches on all sides; these branches in their
turn, send down long slender roots, like those of the Banyan
fig tree (Ficus Lndica), which, rapidly elongating, descend from
all varieties of height, and reaching the water, penetrate the
mud, becoming in time independent trees ; thus a complicated
labyrinth of vegetation is at length formed, serving to arrest
the particles of soil washed down from the interior ; these, by
their accumulations, raise the level of the ground, till at length
what had been water, is converted into a salt marsh ; and what
had been a salt marsh, becomes progressively dry land, fit for
the cultivation of man, and teeming with fertility from its
copious intermixture with the exuvise of marine animals and
vegetables/' The author of this description, compares the germi-
nation of the Mangrove to that of the Banyan, in "- sending
down long slender roots ;" but it must be borne in mind, that
these roots in the Rldzopliora, are not spongioles, borne at the
ends of the branches, but are the true radicles, and the only
difference to the general law of vegetable life, is that they germi-
nate before leaving their parents, so that the long stick-like pro-
tuberance from the fruit, is the young root, which reaches
downwards towards the ground as far as possible, and when no
longer able to hold on to the parent, drops into the mud below,
and then sends out its rootlets ; the rudiments of which are
clearly distinguishable on the surface of the radicles, as they
hang from the trees.

Dampier, in his voyages, says : " The Red Mangrove
groweth commonly by the sea-side, or by rivers and creeks.
It always grows out of many roots about the bigness of a man's
leg, some bigger, some less, which, at about six, eight, or ten
feet above the ground, join into one trunk or body that seems
to be supported by so many artificial stakes. Where this sort
of tree grows it is impossible to march by reason of these
stakes, which grow so mixed one among another that I have,
when forced to go through them, gone half a mile and never
set my foot on the ground, stepping from root to root. The
timber is hard, and good for many uses ; the inside of the
bark is red, and it is used for tanning of leather very much
all over the West Indies."

In places where Mangroves abound, the propagation is
effected by the simple and natural process of the germinating
seeds dropping into the mud and immediately throwing out
their rootlets. The fruit, before germination takes place, is
described as being edible and of a sweet flavour, the juice of
which is fermented and made into a kind of wine. The
economic uses of the Mangrove are very many. A kind of

68 The Mangrove and its Allies.

rough salt is extracted in Borneo from the aerial roots, and
the wood is considered the best firewood of any produced in
the island. The bark is well known as a tanning bark, for
which purpose it is much valued ; indeed, it has been said to
equal, if not to excel, oak bark in the quantity of tannin
which it contains. It is also used for dyeing, producing, in
conjunction with mineral salts, olive, brown, and slate colours.

It is not the bark alone that contains tannin, but all parts
of the plant. The leaves and roots of some of the species are
used in the Mauritius and the West Indies for poultices ; and
in the last-named islands, as well as in the Phillipines, the bark
is considered a good febrifuge. There are four or five species
of Rhizphora known.

Ceriops stands next to Rhizophora in scientific classifica-
tion. Two or three species are described, natives of Eastern
Africa, Asia, Australia, and Polynesia. One of the distinctive
characters of this genus is the five parted persistent calyx ;
the petals, also in fives, are pubescent or hairy at their points ;
and the ten stamens are seated two together in front of the
petals. The bottom part of the ovary has three cells, each cell
containing two ovules, the upper part of the ovary terminating
in a long style, and the seed germinates before leaving the tree
in a similar manner to that of Rhizophora.

Kandelia is a genus of which but one species is known,
namely, Kandelia Rheedii} W. et A. It is a native of the East
Indian Islands. The parts of the flowers of this, like the last-
named genus, are in fives, but it is distinguished chiefly by the
petals being divided and sub-divided into numerous fine divi-
sions, and seated in a fleshy rim or disk, which lines the calyx
tube. The stamens are indefinite, the filaments very fine, and
the anthers small and oblong. The flowers are white and
green; the fruit is ovoid,, coriaceous, one-celled, and one-
seeded, germinating on the trees as in Rhizophora. The
bark of this tree, mixed with ginger or long pepper, and rose-
water, is a reputed medicine among the native practitioners in
India for the cure of diabetes.

Brugueira is a genus having six or eight species, natives of
Eastern Africa, Australia, and the Polynesian Islands. They
are trees frequenting the shores of rivers and muddy swamps,
and are known from the preceding genera by the numerous
lobes or limbs of the calyx, varying from eight to about four-
teen, which adhere to the ovary below, thus making the calyx
superior, or seated above the fruit, and standing up in a whorl
round the radicle. From this arrangement of the sepals, the
radicle might easily be mistaken for an elongated fruit. The
petals agree in number with the sepals; they are coriaceous,
and woolly at the edges, and cleft or divided in two parts.

The Mangrove and its Allies. 69

The number of stamens are from sixteen to twenty-eight, and
are placed as in Kandelia, in pairs, opposite the petals, and each
petal is folded so as to • form a hiding-place for the filament.
The ovary has from two to four cells, each cell containing two
ovules. The fruit being inferior, and the calyx persistent, it
remains at the apex of the fruit ; and when germination takes
place, it is simply pushed away from the centre to make room
for the young radicle. In this genus the roots are thrown up
from below all round the root, as shown in plate.

The internal structure of the main root of the mangrove
(Rhizophora Mangle, L.), as shown in a cross section, differs from
that of the radicle. A good idea of the former may be li id
from Fig. 4, the outer and the central parts of which are
masses of reddish brown fibrous tissue, while the ring is a very
white, hard, woody substance, with clear and distinct rays
crossing it in a direct line. A section of the radicle shows in
the centre a mass of loose fibre surrounded by woody tissue,
made up of silky fibrous bundles, the whole of a similar
colour to the true root. The outer covering is composed of
fine bundles of close, hard, woody fibre, arranged more or less
regularly parallel.

The root of Brugueira shows in a cross section (Fig. 5) a
similar arrangement to that of Rhizophora, except that the
portion between the outer epidermis, or cuticle, and the ring of
wood, is composed of thin paper-like divisions, regularly
arranged, instead of an indiscriminate mass of fibrous tissue.
These divisions, as will be seen by the figure, are very evenly
placed, radiating from the centre. The appearance of one of
these papery walls under the microscope is very singular and
beautiful, presenting a mass of fine, glittering, scale-like
markings.

DESCRIPTION OF THE PLATE.

FIG. 1. — Mangrove tree, Rhizophora Mangle, L. To the
right is seen a tree of Brugueira sp., showing its singular
manner of throwing up its roots.

FIG. 2. — Germinating fruit and portion of the radicle of
Rhizophora Mangle, L., showing the inferior calyx.

FIG. 3. — Germinating fruit and radicle of Brugueira sp.,
showing the superior calyx. This is here represented as being
reflexed, having been drawn from a dried specimen. It stands
erect when fresh.

FIG. 4. — Cross section of root of mangrove, Rhizophora
Mangle.

FIG. 5. — Cross section of root of Brugueira sp.

70 The Mammoth and its Epoch.

THE MAMMOTH AND ITS EPOCH.*

THE discovery of the bodies of enormous animals akin to the
elephant in the frozen soil of Siberia has excited the astonish-
ment of naturalists and of the vulgar. The primitive noniads
regarded them as monstrous burrowing rats, whose life was
extinguished as soon as they saw the light of day ; and the
Chinese supposed that their subterranean movements gave
rise to earthquakes. It has been generally supposed that
Siberia had, in the mammoth days, a, much warmer climate ;
M. de Middendorff disputes the conclusion, and states that the
wood found in N. Siberia, and supposed to have grown there,
is in reality drift-wood. It is also remarked, that the hypo-
thesis of former heat in the Siberian climate would not solve
the enigma, as it would not explain the good preservation in
which the bodies of the great animals has been kept, which
would seem only possible in a frozen soil, and the climate
could not have changed so suddenly as to leave no time for
their decomposition. Besides, the mammoths were well fur-
nished with hair, and were not intended, like the modern
elephants, to inhabit hot countries. Fir needles have been
found between the teeth of rhinoceri, buried by the side of the
mammoth, indicating that the latter may have lived in forests
of conifers ; but what was its food in the steppes which are
beyond the limits of arborescent vegetation ? M. de Midden-
dorff supports the opinion that the bodies of the mammoths
were drifted from more southern regions ; but if this were the
case, how is it that their bodies came to be so perfectly pre-
served in ice, and how was the congelation effected ? Is it
possible, as Adams thinks, that they found their sepulture in
the midst of pure compact ice, and have been preserved there
for millions of years ?

On the recommendation pf M. de Middendorff, the St.

irsburg Academy offerecf'rewards of 100 to 150 roubles for
the discovery of a complete mammoth skeleton, and of 300
roubles for that of a body with the soft parts entire. At
Christmas, J8G5, M. K. C. Von Baer received from Barnaul
••a notification that a Samoycde-Jurack had found an entire
mammoth in 1864, with its skin, near the Bay of Tas, which
opens into the Gulf of Obi.

This discovery, which was mentioned in former numbers of
the i ';, induced the Academy of St. Pel

burg to send M. Fred'Tic Schmidt to the spot. On the 2-ltli
March (last) he arrived at 5Tenissek, and from thence for-
warded a piece of the mammoth's skin, which had been
* Abridged from an article in the Archives des Sciences, No. 108.

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