Although much of Cambodia is heavily forested, the central lowland region is covered with rice paddies, fields of dry crops such as corn (maize) and tobacco, tracts of tall grass and reeds, and thinly wooded areas. Savanna grassland occur in the plains, with the grasses reaching a height of 5 feet (1.5 metres). In the eastern highlands the high plateaus are covered with grasses and deciduous forests. Broad-leaved evergreen forests grow in the mountainous areas to the north, with trees 100 feet (30 metres) high emerging from thick undergrowths of vines, rattans, palms, bamboos, and assorted woody and herbaceous ground plants. In the southwestern highlands, open forests of pines are found at the higher elevations, while the rain-drenched seaward slopes are blanketed with virgin rainforests growing to heights of 150 feet (45 metres) or more. Vegetation along the coastal strip ranges from evergreen forests to nearly impenetrable mangroves.