This alpine valley, formed by retreating glaciers, remains snow-covered from November to May. When the ice thaws in June, the valley is rich with herbs, medicinal and flowering plants, which burst into a profusion of colour in July and August. The month between mid-July and mid-August is the ideal time to visit. At an altitude ranging from 3,350 m to the peak of Gauri Parbat at 6,719 m, the Valley of Flowers is essentially the catchment area of the Pushpawati River, which is known as the Bhyundar Ganga, downstream of Ghangria. It consists of a glacial corridor, 7 km long and 2 km wide, with it's source in the Tipra Glacier which descends from Gauri Parbat. The northern slopes are thickly forested with birch, rowan and rhododendron up to an elevation of 3,800 m with lichens carpeting the ground. The southern slopes at the base of the rock wall consist largely of meadows or bugyals, with a variety of alpine flowers, including anemones, asters, fritillarias, gentians, geraniums, larkspurs, lilies, orchids, poppies including the Himalayan blue poppy, potentillas and primulas, marsh marigolds. Medicinal herbs, such as rhubarb and aconite, are also found in the valley and Brahma Kamal, the celestial flower which is offered to the gods, grows on the higher reaches.