An icon of sub-Saharan Africa, the baobab tree (Adansonia digitata) is a plant that any non-botanist can readily identify. Its silvery smooth bark is
distinctive, whereas its huge size and chubby looks mark it as distinct from any other tree.
Of the eight baobab species only one is found in continental Africa, whereas another occurs in northwestern Australia. But six species occur in Madagascar—a biodiversity
hotspot for this remarkable living being.
Africans and the animals also regard this as a special tree. Africans tell that it is an upside down tree, cast into the ground by angry gods so it landed
branches first, its roots reaching for the sky. Some Africans that spirits live in the baobab's flowers—f you pick a flower you are sure to be eaten by a lion. The golden
velvety pods, about the size of a fist, hold dark bean-like seeds that are coated in a soft powdery flesh rich in vitamins and irresistable to elephants and humans alike. The name
may have come from the Arabic "bu hibab" which means "many-seeded fruit."
A visitor to the arid savannas of Africa will ask themselves, "Why is this tree so common?" Indeed, dotted here and there across vast landscapes, the baobab seems
immune from the ravages of hungry herbivores, drought and the axe. To some extent, it is. Once a baobab gets big enough (80 feet high, 40 feet across), it's leaves are
way out of reach of even the biggest animals, giraffes and elephants. Its broad stubby trunk and immense size make it difficult for elephants to push over, which they are
wont to try when hungry. During the dry season, the baobab drops its leaves—reducing water loss and also making it less tempting for elephants.
The silvery skin-like bark may be another adaptation to high temperatures since it reflects heat better than a dark-colored bark would. Why is the bark so smooth? Maybe it
causes elephants to slip when they try to push the tree over, but it also makes the tree hard to climb for monkeys and small herbivores. This reflective property may also
protect the tree from bush fires.
Baobabs are useless for lumber or firewood—perhaps a good thing these days when so many other trees are used for building houses, carvings and so on. Baobab wood is very
fibrous and spongy, which helps it store water. When someone takes an axe to the tree, it literally bounces off! Chainsaws get clogged up and stop dead. Lucky for the baobab
that its adaptations to conserve water also help it survive the depredations of people and hungry animals. Indeed, baobabs live a long time. It's hard to say exactly how long,
as they do not have growth rings like most trees. Instead, scientists use carbon dating, the same method used on archaeological artifacts. These studies have given ages for
baobabs of at least 1,000 years, while 2,000 years seems possible. It's interesting to contemplate the kind of world a baobab growing today will experience during its lifetime...
|
|