Flame tree. Burning flowers, fountain trees, bract trees and flame trees are the national trees of Gabon. It is a deciduous tree of Osmundaceae, also known as bract calyx, native to Africa. Its flowering period is between winter and spring, and the flowers are cup-shaped. The tree is about10m high and12cm long, with a large crown. It is often used as shade trees or street trees, and is also suitable for planting in parks, communities and tourist areas.