Vachellia xanthophloea
Vachellia xanthophloea is a tree in the family Fabaceae, commonly known in English as the fever tree. This species of Vachellia is native to eastern and southern Africa. It has also become a landscape tree in other warm climates, outside of its natural range.
Description
The trees grow to a height of. The characteristic bark is smooth, powdery and greenish yellow, although new twigs are purple, flaking later to reveal the characteristic yellow. It is one of the few trees where photosynthesis takes place in the bark. Straight, white spines grow from the branch nodes in pairs. The leaves are twice compound, with small leaflets. The flowers are produced in scented pale cream spherical inflorescences, clustered at the nodes and towards the ends of the branches. The pale brown pods contain 5–10 elliptical, flattened green seeds and are long, straight, flat and rather papery, the segments are mostly longer than they are wide, often breaking up to form small clusters of segments each containing an individual seed. As the pods mature they change colour from green to pale greyish brown.Fever trees are fast growing and short lived. They have a tendency to occur as single-aged stands, and are subject to stand-level diebacks that have been variously attributed to elephants, water tables, and synchronous senescence.
Etymology
The name xanthophloea is derived from Greek and means "yellow bark". The common name, fever tree, comes from its tendency to grow in swampy areas: early European settlers in the region noted that malarial fever was contracted in areas with these trees. It is now understood that malarial fever is spread by mosquitos living in the swampy areas that often support this tree species, and not by the tree species itself. This is because mosquitos often lay eggs in moist swampy areas, which they need blood to do.Ecology
Vachellia xanthophloea is found growing near swamps, riverine forests or on lake shores, in semi-evergreen bush land and woodland where there is a high groundwater table. In seasonally flooded areas it often forms dense single species stands.The leaves and pods are used to provide food for livestock while the young branches and foliage are eaten by African elephants while giraffe and vervet monkeys eat the pods and leaves. The flowers are used for foraging by bees and provides favoured nesting sites for birds. Like other acacias and Fabaceae it is a nitrogen fixer, so improves soil fertility. The gum is part of the diet of the Senegal bushbaby especially in the dry season.
Butterflies recorded as feeding on Vachellia xanthophloea in Kenya included the Kikuyu ciliate blue, Pitman's hairtail, common ciliate blue, African babul blue, Victoria's bar and common zebra blue. In addition 30 species of larger moths have been recorded as feeding on this tree.