Minecraft wiki entry for Model, associated text: To create the usual shape of the saplings, both elements are being rotated by 45 degrees. Therefore, the origin and the axis of rotation are set to the specified values, the angle is set to 45 degrees and "rescale" is set to true. The latter causes the model to be scaled on the axes it has not been rotated on, so that it takes up the same space as it did before rotating it (see comparison images).