Minecraft wiki entry for Development_versions, associated text: A new swamp biome with teal water that often generates in warmer clusters, usually next to jungles and deserts.
Contains mangrove trees, a new type of tree.
Has an unique shape, with a root system of mangrove roots leading up to a forking trunk and mangrove leaves.
It has a chance to generate a bee nest.
Grows from mangrove propagules.
Naturally spawns warm frogs and slimes, but there are no sheep, cows, pigs or chickens.
Does not generate witch huts.
The floor is coated with a single layer of mud.