the drier inner Himalayan valleys. From mid April to June temperatures are moderate to cool (19 °C maximum). The Valley of Flowers also has the micro-climate of an enclosed inner Himalayan valley, and is shielded from the full impact of the southwest summer monsoon by the Greater Himalaya range to its south. There is often dense fog and rain especially during the late summer monsoon. Both Basin and Valley are usually snow-bound for six to seven months between late October and late March, the snow accumulating deeper and at lower altitudes on the shadowed southern than on the northern side of the valleys. Ecology Biodiversity The Valley of Flowers is a high-altitude Himalayan valley that has long been acknowledged by renowned mountaineers, botanists, and in literature. It has been recognized internationally for over a century and is referenced in the Hindu religion. Local people have visited the valley since ancient times. Indian yogis are known to have visited the valley for meditation. The Valley of Flowers has many different colourful flowers, taking on various shades of colours as time progressed. The Valley of Flowers has gained importance as a region containing a diversity of alpine flora, representative of the Western Himalayan alpine shrub and meadows ecoregion. The rich diversity of species reflects the valley's location within a transition zone between the Zanskar and Great Himalayas ranges to the north and south, respectively, and between the Eastern Himalaya and Western Himalaya flora. A number of plant species are considered threatened. Several have not been recorded outside of Uttarakhand. Two have not been recorded in Nanda Devi National Park. The diversity of threatened species of medicinal plants is higher than has been recorded in other Indian Himalayan protected areas. The entire Nanda Devi Biosphere Reserve lies within the Western Himalayas Endemic Bird Area (EBA). The Valley of Flowers National Park is the second core zone of the Nanda Devi Biosphere Reserve. Seven restricted-range bird species are endemic to this part of the EBA. Flora Three types of sub-alpine zones The valley has three types of sub-alpine zones as follows: foothills alpine between 3,200 m and 3,500 m which is the upper height limit for trees, lower alpine between 3,500 m and 3,700 m, and higher alpine above 3,700 m. The habitats include valley bottom, river bed, small forests, meadows, eroded, scrubby and stable slopes, moraine, plateau, bogs, stone desert and caves. The