Source Naturals Pau D'Arco Extract contains 300% more active ingredient than whole pau d'arco. These active constituents are molecularly unbound and freed from the plant fiber. This product is derived from the highest quality inner bark of the purple lapacho tree found in Brazil and Northern Argentina. Ever since ancient times, when it was a standard for the medicine men of the Inca Empire, pau d'arco (also known as ipe roxo and taheebo) has been one of the most widely used herbs in South America. Its popularity is attributed to the key constituent, lapachol, which has been the subject of numerous scientific studies.