Biomes are large expanses of the earth's surface covered by plants with a similar growth form.
The main terrestrial biomes include tundra, conifer forests, temperate deciduous forest, grasslands, deserts, schlerophyll scrub forest, tropical deciduous forest, tropical rainforest. Species composition may vary between different instances of a given biome, but the overall growth form, and the adaptations of plants and animals, will be similar. The distribution of biomes is determined by regional climates found in different areas of the earth. The principle factors involved are mean temperature and mean precipitation, although seasonality can be important in establishing some biomes. The boundries between biomes are typically not so sharp and well-defined.