Baobab flowers open so fast you can watch them move
Baobabs, the 'upside down trees', rank among the longest-lived vascular plants, yet their flowers are fertile for at most 15 hours. They unfurl around dusk quickly enough to see, shed pollen overnight, usually for visiting bats, and have withered stigmas by morning. Meanwhile, southern Africa's baobabs began dying rapidly this century for reasons still unknown.
The genus Adansonia holds eight species native to Africa, Australia and Madagascar, and genomic and ecological analysis points to Madagascar as its birthplace. People have carried baobabs to Asia and the Caribbean; several trees in Barbados are thought to have come from Africa. The name honours the French naturalist Michel Adanson, who gave the first detailed description and drawings of the African baobab, Adansonia digitata.
Size varies a lot. The Australian A. gregorii rarely passes 10 metres and often has several trunks, while most species reach 25 to 30 metres with trunks 2 to 3 metres across. The African baobab can develop trunks up to 10 metres in diameter. Young trees are slender with swollen bases; mature ones swell into bottles or cylinders. Their fibrous wood forms rings, but not every year, so rings cannot date a tree. Trunk girth rises and falls with rainfall, suggesting the tree stores water inside. Leaves, made of five to eleven leaflets fanned like fingers, drop in the dry season.
The flowers are large, fragrant and short-lived in function even if they cling on for days. A five-lobed calyx splits and curls back, revealing silky inner surfaces in cream, pink or red, around a tube of fused stamens from which a long style emerges. Petals range from white to bright yellow to dark red and fade fast. Only the African baobab dangles its flowers and fruit on long hanging stalks; the rest hold them on short stalks near the shoot tips. The fruit are large berries with kidney-shaped seeds packed in dry pulp.
The recent die-off has puzzled scientists. Blight or insect pests seem unlikely to kill such giants so quickly, so some suspect mass dehydration, though the cause has not been established.
Source: Adansonia
