SNAKE-TREE.
In other cases we find the roots fantastically spreading and revelling in a variety of grotesque shapes, such as we nowhere find in the less exuberant vegetation of Europe. Thus, in the india-rubber tree (Ficus elastica), masses of the roots appear above ground, extending on all sides from the base, and writhing over the surface in serpentine undulations, so that the Indian villagers give it the name of the snake-tree. Sir Emerson Tennent mentions an avenue of these trees leading to the botanical garden of Peradenia, in Ceylon, the roots of which meet from either side of the road, and have so covered the surface as to form a wooden framework, the interstices of which retain the materials that form the roadway. These tangled roots sometimes trail to such an extent that they have been found upwards of 140 feet in length, whilst the tree itself was not thirty feet high.
The roots of the Mangroves, which in the tropical zone are found fringing the shores of the sea, or the mouths of rivers, wherever the reflux of the tide exposes a broad belt of alluvial soil, are admirably adapted for securing a footing on the unstable brink of the ocean.
MANGROVE.
The growth of these salt-water-loving trees (Rhizophora gymnorrhiza, R. Mangle) is equally peculiar and picturesque. The seeds germinate on the branches, and, increasing to a considerable length, finally fall down into the mud, where they stick, with their sharp point buried, and soon take root.
As the young mangrove grows upwards, pendulous roots issue from the trunk and low branches, and ultimately strike into the muddy ground, where they increase to the thickness of a man’s leg; so that the whole has the appearance of a complicated series of loops and arches, from five to ten feet high, supporting the body of the tree like so many artificial stakes.
It may easily be imagined what dense and inextricable thickets, what incomparable breakwaters, plants like these—through whose mazes even the light-footed Indian can only penetrate by stepping from root to root—are capable of forming.
Their influence in promoting the growth of land is very great, and in course of time they advance over the shallow borders of the ocean. Their matted roots stem the flow of the waters, and, retaining the earthy particles that sink to the bottom between them, gradually raise the level of the soil. As the new formation progresses, thousands of seeds begin to germinate upon its muddy foundation, thousands of cables descend, still farther to consolidate it; and thus foot by foot, year after year, the mangroves extend their empire and encroach upon the maritime domains.
The enormous deltas of many tropical rivers partly owe their immense development to the unceasing expansion of these littoral woods; and their influence should by no means be overlooked by the geologist when describing the ancient and eternal strife between land and ocean.