Minecraft wiki entry for Tree, associated text: Depending on where the tree generates, the color of the leaves may differ. For example, if an oak tree is in a colder biome, such as a taiga or windswept hills biome, it has a blue-green hue. In a snowy taiga, the leaves are white with a slight grey tint. However, if it is in a dry biome, such as a desert or savanna, it has a mustard yellow hue. Birch leaves do not follow these rules; it is always the same color regardless of the biome.