Taisha is again the author of today’s entry:
Today’s photo is of the fony baobab or Adansonia rubrostipa. This picture of a cultivated plant was taken by Archived Photos@Flickr at the Cleveland Botanical Garden’s Eleanor Armstrong Smith Glasshouse on August 27. 2010 ( via the Botany Photo of the Day Flickr Pool). Thanks for the image!
Adansonia rubrostipa of the Malvaceae is one of eight or nine species in the genus. Adansonia has a Southern Hemisphere distribution, with six members being endemic to Madagascar (including the fony baobab), one endemic to Australia, and one, Adansonia digitata, native to mainland Africa (though a recent paper recognizes an additional species on mainland Africa). Adansonia digitata is also cultivated by humans throughout the tropics. Originally, it was thought that the distribution of the genus could be explained by continental drift. However, it is now thought that the ancestor of the Australian species arrived via long-distance dispersal by water, and subsequently evolved on that continent over “only” the past 30 million years.
Adansonia rubrostipa is a deciduous tree that can reach up to 20 meters in height. Its huge trunk is covered with a bark of reddish-brown. From the trunk extend both horizontal and erect branches. The palmately-compound leaves are arranged spirally. In the axils of the leaves, the solitary flowers are borne. These large and showy flowers have bright yellow-orange petals, numerous stamens that extend past the corolla, and a lobed stigma of bright red. The fruit is a large woody globose berry containing many kidney-shaped seeds (see: Baum, D. A. (1995). A systematic revision of Adansonia (Bombaceae). Annals of the Missouri Botanical Garden. 82(3): 440-471).
Baobabs are divided into three sections based on the floral morphology of the floral bud shape, the orientation of the flower, and the length of the staminal tube. Adansonia rubrostipa is from the section Longitubae (the other two sections are Adansonia and Brevitubae). Due to their variation in floral morphology, an assortment of pollinators visit species of Adansonia, including bees, flies, butterflies, settling moths, hawkmoths, birds, non-flying mammals, and bats. The main pollinator of the fony baobab is the long-tongued hawkmoth (Coelonia solani), which is attracted to the sweet-smelling nocturnal flowers. These visitors often approach the flower from the front and insert their long proboscis toward the nectary when they are still 10cm away from the flower! Their proboscis passes the filaments of the flower. The up and down movement of hovering facilitates pollen-collection on the moth’s wings and body. This pollen is then transferred to the red stigma and style. Nocturnal lemurs are also known to visit the flowers of the fony baobab in search for nectar, and while doing so can transfer pollen from anther to stigma. However, these mammals can cause some damage to the flowers, so their overall effectiveness is questioned (see: Baum, D. A. (1995). The comparative pollination and floral biology of baobabs (Adansonia– Bombaceae). Annals of the Missouri Botanical Garden. 82(2): 322-348.).