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 Purple Fruited Pea Eggplant (Solanum trilobatum)   

Purple Fruited Pea Eggplant is a thorny creeper with bluish violet flower, more commonly available in Southern India has been used traditionally in Siddha system of medicines to treat various diseases. Ref:
http://www.flowersofindia.in/catalog/slides/Purple%20Fruited%20Pea%20Eggplant.html