Aquilaria is a genus of trees, called lign aloes or lign-aloes trees, in the family Thymelaeaceae. It includes 21 species native to southeast Asia. They occur particularly in the rainforests of Indonesia, Thailand, Cambodia, Laos, Vietnam, southern China, Malaysia, Northeast India, Bangladesh, the Philippines, Borneo and New Guinea. The trees grow to 6–20 m (20–66 ft) tall. The leaves are alternate, 5–11 cm (2.0–4.3 in) long and 2–4 cm (0.79–1.6 in) broad, with a short acuminate apex and an entire margin. The flowers are yellowish-green, produced in an umbel; the fruit is a woody capsule 2.5–3 cm (0.98–1.2 in) long.