Anogeissus leiocarpa (DC.) Guill. & Perr.
A. schimperi Hochst. ex Hutch. & Dalziel).
Eng.: African birch. Fre.: Bouleau africain.
Evergreen tree, up to 15(20) m in height, that in rainy tropical areas can reach up to 30 m. Very large crown, especially when it grows isolated, with somewhat pendant branches in older specimens. Trunk straight, up to 1 m in diameter, with light grey to dark brown bark, frequently spotted, fibrous, that peels off in rectangular sheets. When the trunk is wounded, it exudes a dark resin. Young branchlets pubescent. Leaves oblong, oblong-lanceolate or oval-lanceolate, with acute or obtuse apex, alternate or subalternate, simple, entire, glabrous, the younger ones sericeous. Inflorescence in terminal head. Flowers pentamerous, very fragrant, pale yellow in colour, without petals. Ovary inferior. Fruit a subglobose samara, 4-10 × 6-11 × 2-2.25 mm, with 2 wings, from brown-yellowish to brown-reddish, indehiscent. Seed 1, horizontally enclosed.
Flowering:
During the summer, coinciding with the rainy season.
Fruiting:
About 2 months after flowering.
Habitat:
From the driest savannahs to the edges of the most humid forests (but not within them), in rocky areas, with little soil, but also in silty-sandy floodplains, in wooded grasslands, in thickets and river banks. It tolerates drought and relatively high humidity, 200-1,200 mm of average anual rainfall. It is one of the first trees to grow after a disturbance (such as a fire or a flood), but its capacity for colonisation is severely impaired by its very slow inicial growth and by its high sensitivity to fire. Its altitudinal range is wide, from sea level to 1,900 m.
Distribution:
North of tropical Africa, reaching the northern DR Congo to the S. It does not seem to reach the Equator. In North Africa, it is broadly distributed throughout the Sahel, from Mauritania and Senegal to the W, to Sudan and Eritrea to the E.
Observations:
Traditionally, this tree has been used for multiple purposes, but did not use to be cut down. In Burkina Faso, it is a sacred tree, highly valued and respected, named “siiga”, which means “the soul”. Among its values is the good quality of the wood, known as “cane” in the market. It is also an excellent fuel and produces good charcoal, and for this reason thousands of big trees have been felled in recent decades. Currently, although they continue to be cut, it is being used increasingly in reforestation and to stabilise the river banks.
Conservation status:
Species becoming less common. Currently, it has not been assessed at a global level in the IUCN Red List of Threatened Species.