lower surrounding hills in the buffer zone are thickly forested. The Forest Research Institute in 1992 recorded 600 species of angiosperms and 30 pteridophytes in the valley and surroundings, discovering 58 new records for the valley of which 4 were new for Himalayan state. Of these plants, 5 out of 6 species globally threatened are not found in Nanda Devi National Park or elsewhere in Uttarakhand: Aconitum falconeri, A. balfouri, Himalayan maple (Acer caesium), the blue Himalayan poppy (Meconopsis aculeata) and Saussurea atkinsoni. 31 species of rare and endangered categories were observed within the national park in 1998. Further his studies report that the dominant family in Valley of Flowers is Asteraceae with 62 species. 45 medicinal plants are used by local villagers and several species, such as Saussurea obvallata (brahmakamal) are collected as religious offerings to goddesses Nanda Devi and Sunanda Devi. The site is designated a Centre of Plant Diversity. Characteristic of the sub-alpine zone are high altitude forests which help to retain moisture and snow and support a large number of floral and faunal communities. It is dominated by the uncommon Himalayan maple Acer caesium (VU), west Himalayan fir Abies pindrow, Himalayan white birch Betula utilis, and Rhododendron campanulatum with Himalayan yew Taxus wallichiana, Syringa emodi and Sorbus lanata. Some of the common herbs are Arisaema jacquemontii, Boschniakia himalaica, Corydalis cashmeriana, Polemonium caerulium, Impatiens sulcata, Geranium wallichianum, Galium aparine, Morina longifolia, Inula grandiflora, Nomochoris oxypetala, nemone rivularis, Pedicularis pectinata, P. bicornuta, Primula denticulate and Trillidium govanianum. In trampled areas where past livestock congregated, Himalayan knotweed Polygonum polystachium is a rampant weed. Flowers The flowers were surveyed and inventoried in 1987 by the Botanical Survey of India, in 1992 by the Forest Research Institute and in 1997 by the Wildlife Institute of India which found five species new to science. Flowers mostly orchids, poppies, primulas, marigold, daisies and anemones carpet the ground. Sub-alpine forests of birch and rhododendron cover parts of the park's area. A decade long study by C.P. Kala from 1993 onward concludes that the Valley of Flowers is endowed with 520 species of higher plants (angiosperms, gymnosperms and pteridophytes), of these 498 are flowering plants. The park has many species of medicinal plants including Dactylorhiza hatagirea, Picrorhiza kurrooa, Aconitum violaceum, Polygonatum multiflorum, Fritillaria roylei and Podophyllum hexandrum. Fauna Species diversity The density of wild animals in the valley is not high, but all the animals