THORNY PLANTS— MANGROVES. 



537 



and sbarp as the bill of a sparrow-hawk. The black twigs of the buffalo-thorn (Acacia 

 latronum)f a low shrub, abounding in northern Ceylon, are beset at every joint by a 

 pair of thorns set opposite each other, like the horns of an ox, as sharp as a needle, 

 from two to three inches in length, and thicker at the base than the stem they grow 

 on; and the Acacia tomentosa, another member of the same numerous genus, has 

 thorns so large as to be called the jungle-nail by Europeans, and the elephant-thorn 

 by the natives. In some of these thorny plants, the spines grow, not singly, but in 

 branching clusters, each point presenting a spike as sharp as a lancet; and where 

 these shrubs abound, they render the forest absolutely impassable, even to animals of 

 the greatest size and strength. The formidable thorny plants of the torrid zone, which 

 are often made use of by man to protect his fields and plantations against wild beasts 

 and robbers, have sometimes even been made to serve as a bulwark against hostile 

 invasions. Thus Sir Emerson Tennent informs us, that during the existence of the 

 Kandyan kingdom, before its conquest by the British, the frontier forests were so 

 thickened and defended by dense plantations of thorny plants, as to form a natural 

 fortification impregnable to the feeble tribes on the other side ; and at each pass which 

 led to the level country, movable gates, formed of the same thorny beams, were sus- 

 pended as an ample security against the incursions of the naked and timid lowlanders. 



In the tropical zone, wherever the reflux of the tide exposes a broad belt of alluvial 

 soil, the shores of the sea, particularly along the estuaries of rivers or in the shallow 

 lagoons, are generally found fringed with a dense vegetation of Mangroves. For no 

 plants are more admirably adapted for securing a footing on the unstable brink of the 

 ocean, — none are better formed to lead an amphibious life. The growth of these salt- 

 water loving trees 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. The fruits of 

 many plants are furnished with wings, that the winds may carry them far away and 

 propagate them from land to land; others, enveloped in hard, water-proof shells, float 

 on the surface of the sea, and are wafted by the currents to distant coasts ; but here 

 we have a plant, the seeds of which were destined to remain fixed on an uncertain 

 soil, close to the parent-plant, and surely this end could not have been attained in a 

 more beautiful manner ! 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 appear- 

 ance 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. Their influence in promoting the 

 growth of land is very great, and in course of time they advance over the shallow bor- 

 ders 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. 



A whole world of interesting discoveries would here, no doubt, reward the natural- 

 ist's attention ; but the mangroves know well how to guard their secrets, and to repel 

 the curiosity of man. Should he attempt to invade their domains, clouds of blood- 



