A mangrove is a woody tree or shrub that grows in sheltered, shallow coastal/estuarine regions, especially where fine sediment deposition occurs. There are 54 diverse species of trees/shrubs that can occupy a mangal. Mangroves are interesting in the fact that they are viviparous. The propagules that are released by mangroves can remain viable in the water for extended periods of time until the plant finds a suitable area to establish residency. Mangrove roots provide stability to an unstable, fine sediment environment. They also contain a large amount of surface area for gas exchange. Mangroves come in three basic forms: riverine, tide-dominated, and basin. A riverine mangrove is typically associated in areas with low tidal regime, especially deltas of major rivers and large areas in asia. This form is also influenced by freshwater flow, meaning it is not going to have much influence from changing tides.