Acacia xanthophloea Benth.
Vachellia xanthophloea is a tree in the Fabaceae family and is commonly known in English as the fever tree (local East African names include olerai, kimwea, murera, and mwelele). This species of Vachellia is native to eastern and southern Africa. It can be found in Botswana, Kenya, Malawi, Mozambique, Somalia, South Africa, Swaziland, Tanzania, Zambia and Zimbabwe. It has also become a landscape tree in other warm climates, outside of its natural range.
The trees grow to a height of 15–25 m. The characteristic bark is smooth, powdery and greenish-yellow in colour. 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 (8×2 mm). The flowers are produced in scented pale cream spherical inflorescences, clustered at the nodes and towards the ends of the branches.
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.
The name xanthophloea is derived from Greek and means "yellow bark" (ξανθός "yellow, golden"; φλοιός "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. 
It is a host for the root parasite Sarcophyte sanguina.
In popular culture
These trees are immortalized by Rudyard Kipling in one of his Just So Stories, The Elephant's Child, wherein he repeatedly refers to "the great grey-green, greasy Limpopo River, all set about with fever-trees."
Notes and references
- Kyalangalilwa B, Boatwright JS, Daru BH, Maurin O, van der Bank M. (2013). "Phylogenetic position and revised classification of Acacia s.l. (Fabaceae: Mimosoideae) in Africa, including new combinations in Vachellia and Senegalia.". Bot J Linn Soc 172 (4): 500–523. doi:10.1111/boj.12047.
- Western, D. & C. Van Praet (1973). "Cyclical changes in the habitat and climate of an East African ecosystem". Nature 241 (5385): 104–106. doi:10.1038/241104a0.
- Young, T.P. and W.K. Lindsay (1988). "Role of even-aged population structure in the disappearance of Acacia xanthophloea woodlands". African Journal of Ecology 26: 69–72. doi:10.1111/j.1365-2028.1988.tb01130.x.
- Ruess, R.W. and F.L. Walter (1990). "The impact of large herbivores on the Seronera woodlands, Serengeti National Park, Tanzania". African Journal of Ecology 28 (4): 259–275. doi:10.1111/j.1365-2028.1990.tb01161.x.
- Mills, A.J. (2006). "The role of salinity and sodicity in the dieback of Acacia xanthophloea in Ngorongoro Caldera, Tanzania". African Journal of Ecology 44: 61–71. doi:10.1111/j.1365-2028.2006.00616.x.
- Vachellia xanthophloea (as Acacia xanthophloea) entry at PlantZAfrica.com
- "The Elephant's Child
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- Pooley, E. (1993). The Complete Field Guide to Trees of Natal, Zululand and Transkei. ISBN 0-620-17697-0.
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