More than two-thirds of palms live in tropical forests, where some species grow tall enough to form part of the canopy and other shorter palms form part of the understory. Some kinds form pure stands in areas with poor drainage or regular flooding. Other palms live on tropical mountains above 1000 meters, Palms may also live in grasslands and scrublands, usually where there is water, and in desert oases. A few palms are adapted to extremely basic lime soils, while others are similarly adapted to very acidic soils.