Because of the steep elevation increase around the pass, the vegetation graduates from sub-tropical forest at its base, to a temperate region, to a wet and dry alpine climate, and finally to cold tundra desert devoid of vegetation. Around Nathu La and the Tibetan side, the region has little vegetation besides scattered shrubs. Major species found in the region include dwarf rhododendrons (Rhododendron anthopogon, R. setosum) and junipers. The meadows include the genera Poa, Meconopsis, Pedicularis, Primula, and Aconitum. The region has a four-month growing season during which grasses, sedges, and medicinal herbs grow abundantly and support a host of insects, wild and domestic herbivores, larks, and finches. The nearby Kyongnosla Alpine Sanctuary has rare, endangered ground orchida and rhododendrons interspersed among tall junipers and silver firs.