Pharmacodynamic and ethnomedicinal uses of weed speices in nilgiris, Tamilnadu State, India: A review

Generally, weeds are considered as nuisances in the garden and enemies to the farmer, as there is a misconception that they are useless. Many of the herbs used in Indian traditional medicine and tribal medicine are considered weeds by agriculturists and field botanists (for example, Phyllanthus amarus L., Eclipta alba L.,Centella asiatica (L.) etc.). Even though many of these weeds have high ethnopharmacological importance, they are being destroyed and there is a lack of scientific knowledge and guidance. In the Nilgiris many medicinally valuable weeds like Achyranthes bidentata Blume., Artemisia nilagirica Clarke., Centella asiaticaL., are very prominent having good therapeutic values like diuretic, antimalarial and brain tonic. The main aim of this review is to expose the important pharmacodynamic and ethnomedicinal values of 50 prominent weeds belongs to 26 different families that grow wild in the Nilgiris. It is possible that some of these weeds could provide an additional income to farmers. There is increasing evidence to support that weeds are relatively high in bioactive molecules thus very important for new drug discovery. Innovative research should be encouraged and scientific workshops conducted by government bodies to communicate the medicinal value of weeds, make weeds economically important and to fill the gap between weeds, farmers and the economy.   Key words: Weeds, pharmacological importance, pharmacodynamic uses, Silybum marianum L., Artemisia parviflora Roxb.