Wildflowers of the Eastern Himalayas
Himalayan vegetation can be broadly classified into four types—tropical, subtropical, temperate, and alpine—each of which prevails in a zone determined mainly by elevation and precipitation. Local differences in relief and climate, as well as exposure to sunlight and wind, cause considerable variation in the species present within each zone.
Tropical evergreen rainforest is confined to the humid foothills of the eastern Himalayas. The evergreen dipterocarps—a group of timber- and resin-producing trees—are common; their different species grow on different soils and on hill slopes of varying steepness. Some 4,000 species of flowering plants, of which 20 are palms, are estimated to occur in the eastern Himalayas.
With decreasing precipitation and increasing elevation westward, the rainforests give way to tropical deciduous forests, which thrive on high plateaus at elevations of about 3,000 feet (900 metres), while dry sal forests prevail higher up, at 4,500 feet (1,400 metres).
The alpine zone begins above the tree line, between elevations of 10,500 and 11,700 feet (3,200 and 3,600 metres), and extends up to about 14,600 feet (4,500 metres) in the eastern Himalayas. In that zone can be found all the wet and moist alpine vegetation.