Adansonia

Adansonia is a genus made up of eight species of medium-to-large deciduous trees known as baobabs (ˈbaʊbæb or ˈbeɪoʊbæb). They are placed in the Malvaceae family, subfamily Bombacoideae. They are native to Madagascar, mainland Africa, and Australia. The trees have also been introduced to other regions such as Asia. The generic name honours Michel Adanson, the French naturalist and explorer who described Adansonia digitata. The baobab is also known as the "upside down tree", a name that originates from several myths. They are among the most long-lived of vascular plants and have large flowers that are reproductive for a maximum of 15 hours. The flowers open around dusk, opening so quickly that movement can be detected by the naked eye, and are faded by the next morning. The fruits are large, oval to round and berry-like and hold kidney-shaped seeds in a dry, pulpy matrix. In the early 21st century, baobabs in southern Africa began to die off rapidly from a cause yet to be determined. It is unlikely that disease or pests would be able to kill many trees so rapidly, and some have speculated that the die-off is a result of dehydration. Baobabs are long-lived deciduous, small to large trees from tall with broad trunks and compact crowns. Young trees usually have slender, tapering trunks, often with a swollen base. Mature trees have massive trunks that are bottle-shaped or cylindrical and tapered from bottom to top. The trunk is made of fibrous wood arranged in concentric rings, although rings are not always formed annually and so cannot be used to determine the age of individual trees. Tree diameter fluctuates with rainfall so it is thought that water may be stored in the trunk. Baobab trees have two types of shoots—long, green vegetative ones, and stout, woody reproductive ones. Branches can be massive and spread out horizontal from the trunk or are ascending. Adansonia rubrostipa is the only baobab that sometimes has spines. Adansonia gregorii is generally the smallest of the baobabs, rarely getting to over tall and often with multiple trunks.