The demand for a rare, fragrant ingredient is threatening the survival of one of the world’s most expensive trees. High-quality agarwood can cost more than $30,000 per kilogram (2.2 pounds), almost as much as gold.

Some trees of the Aquilaria and Gyrinops genus — found in parts of India and southeast Asia — produce agarwood, a resin-soaked, scented bark. Oil from this fragrant agarwood is frequently added to perfumes, incense products, and medicines, and is an integral part of many cultures. Agarwood (also called oud) is especially popular in the Arab countries and Japan.

In fact, agarwood-producing species have been put on the list of the Convention on International Trade in Endangered Species (CITES), and it is now illegal to cut or harvest agarwood-producing species in India and most southeast Asian countries.