Sapling

Saplings are a Decoration Block. In Creative mode, they can be placed freely. Saplings will grow into a full Tree if the server has "grow-trees" set to "true" in the "server.properties" file.

In Survival, Indev and Infdev, saplings appear randomly when tree leaves decay. In order to maximize your chance of finding a sapling, ensure that the leaves are not touching any wood or ground blocks. As the leaves decay, they will randomly drop a sapling, which you can come back and collect.

In Alpha, you can punch away tree leaves, which will randomly drop saplings.

The saplings can be replanted to make a new tree, if they're on a lit dirt tile and have at least 4 blocks of "headroom" above them.