Not only do the roots depending from the branches grasp and colonize new mud, but the seedlings are also specially adapted to fulfil the same office. They remain a long time attached to the parent fruit; they also grow to a considerable length before they fall off. When ready to fall, they have a distinct seedling stem, which swells out towards the base and ends in a pointed root. The seedling is, in fact, like a club hanging upside down and with a pointed end. When it does fall, it goes straight down deep into the mud; then it promptly forms some anchoring roots, and the young mangrove is fixed in new mud and begins to develop. So that the forest continually grows towards the sea. Such mudbanks soon become pierced by roots in every direction. Then the leaves of the mangroves themselves, as well as silt, soil, and rubbish floating in the water, gradually accumulate about and around these roots. This must raise the level of the ground. Eventually the soil becomes hardened and is above the level of the water. When this happens, the mangrove, which likes salt water about its roots, becomes unhealthy and the ordinary jungle trees kill it and take its place. Thus in course of time, when the jungle is cleared, fertile ricefields may be thriving on what was once a pure, or rather impure, mudbank. In this way, by the continual development of the mangroves, enormous stretches of land are being added to the continents, and the process continues so long as the character of the coast-line favours it. The shore-line covered by these mangrove swamps is enormous. In fact, within the tropics one finds them almost everywhere along the seashore, but coral, rock, or an exceedingly dry climate such as that of Arabia or Northern Peru, prevents their growth. Central and South America, West and East Africa, India, Polynesia, Australia, and much of the Asiatic coast-line, is covered by mangroves. [Illustration: _Stereo Copyright, Underwood & Underwood_ _London and New York_ A RICEFIELD IN CHINA The proprietor and two of his coolies are in front of the paddy field. The young rice plants can be seen growing in the water.] Theophrastus speaks of those in the Persian gulf, and that exceedingly shrewd botanist has some valuable notes about them worth reading even to-day.[75] [75] Drude, _l.c._; Schimper, _l.c._; Warming, _l.c._; _Colonial Reports_, No. 3, Miscellaneous. Schimper, _Indo-Malayische Strandflora_. In temperate countries, such as our own, the districts where great rivers enter the sea are for the most part aguish and rheumatic, but, of course, there is nothing so startling and extraordinary as the mangrove swamps. Yet, even in temperate countries, the work of winning or gaining new land plods steadily onwards, and it is performed by humble, inconspicuous little plants.