Cinnamomum cassia, called Chinese cassia or Chinese cinnamon, is an evergreen tree native to southern China, Bangladesh, India, and Vietnam. It is one of several species of Cinnamomum that are used primarily for their aromatic bark, which is used as a spice. In the United States of America, Chinese cassia is often sold under the culinary name of "cinnamon". The buds are also used as a spice, especially in India, and were once used by the ancient Romans. The tree grows to 10–15 m tall, with greyish bark and hard elongated leaves that are 10–15 cm long and have a decidedly reddish colour when young. Cassia is used in traditional Chinese medicine, where it is considered one of the 50 fundamental herbs. Due to a toxic component called coumarin, European health agencies have warned against consuming high amounts of cassia. Other possible toxins founds in the bark/powder are cinnamaldehyde and styrene.