Minecraft wiki entry for Tree, associated text: Tree canopies are composed of leaf blocks and grow 1 block higher than the highest log block (except those of the giant oak tree, whose leaves grow 3 blocks higher). The canopy may begin from the ground and go up to 6 blocks from the ground. Tree canopies are generated from roughly spherical clusters of leaves about 5–7 blocks across, centered on sections of trunk or branches. Leaves must be supported by an adjacent trunk (or leaf blocks connected to the trunk); otherwise, they disappear.