Chestnut (Castanea spp.) is a deciduous tree in the family Fagaceae grown for its edible seeds (nuts). The chestnut tree has a thick trunk covered in gray bark. The trunk has an erect growth habit and can grow 2 m (6.6 ft) in diameter. When the tree stands alone, the canopy can spread 15 m (49 ft) across and is made up of glossy leaves with serrated margins and pointed tips. The leaves are hairy with visible glands on the underside. The chestnut tree produces flowers on long catkins and the seeds are produced in clusters of 1–3. The seeds are covered by a thick, spiny bur which is approximately 10 cm (4 in) in diameter. The kernel within is protected by a thin, dark brown shell. Chestnut trees can reach 40–60 m (131–198 ft) in height and can live for in excess of 150 years. Chestnut may also be referred to by variety and includes European, American, Japanese and Spanish chestnut. The tree originates from Asia.