Uncaria tomentosa is a woody vine found in the tropical jungles of South and Central America. It is known as cat's claw or uña de gato in Spanish because of its claw-shaped thorns.The plant root bark is used in herbalism for a variety of ailments, and is sold as a dietary supplement. Cat's claw has been used as a traditional medicine in South American countries over centuries for its supposed health benefits, and is a common herbal supplement. The part used medicinally is the bark of the vine or root. It is one of the best sellingherbs in the USA.