Four of the 131 medicinal plant species found in Bidar are on the verge of extinction, botanist S.V. Kalmath said at a seminar on Ayurveda recently. In his paper on medicinal plants in Bidar district at the fifth Ayurveda Conference in Bhopal, he said that 29 other species were endangered. These findings were the result of a two-and-a-half year study of medicinal plant species in the district. The study covered the climate, knowledge base of native healers and demographic indicators, according to a release here on Wednesday. — Special Correspondent