Regarded as the largest succulent plant in the world, the baobab
tree is steeped in a wealth of mystique, legend and superstition
wherever it occurs in Africa. It is a tree that can provide, food,
water, shelter and relief from sickness.
Description
Often referred to as 'grotesque' by some authors, the main stem
of larger baobab trees may reach enormous proportions of up to 28
m in girth. Although baobab trees seldom exceed a height of 25 m.
The massive, usually squat cylindrical trunk gives rise to thick
tapering branches resembling a root-system, which is why it has
often been referred to as the upside-down tree. There
is a tale which tells of how God planted them upside-down. Many
traditional Africans believe that the baobab actually grows upside-down.
The stem is covered with a bark layer, which may be 50-100 mm thick.
The bark is greyish brown and normally smooth but can often be variously
folded and seamed from years of growth. The leaves are hand-sized
and divided into 5-7 finger-like leaflets. Being deciduous, the
leaves are dropped during the winter months and appear again in
late spring or early summer.
The large, pendulous flowers (up to 200 mm in diameter) are white
and sweetly scented. They emerge in the late afternoon from large
round buds on long drooping stalks from October to December. The
flowers fall within 24 hours, turning brown and smelling quite unpleasant.
Pollination by fruit bats takes place at night.
The
fruit is a large, egg-shaped capsule (often >120 mm), covered
with a yellowish brown hairs. The fruit consists of a hard, woody
outer shell with a dry, powdery substance inside that covers the
hard, black, kidney-shaped seeds. The off-white, powdery substance
is apparently rich in ascorbic acid. It is this white powdery substance
which is soaked in water to provide a refreshing drink somewhat
reminiscent of lemonade. This drink is also used to treat fevers
and other complaints.
This tree is slow growing, mainly due to the low rainfall it receives.
Distribution
The baobab tree is found in areas of South Africa, Botswana, Namibia,
Mozambique and other tropical African countries where suitable habitat
occurs. It is restricted to hot, dry woodland on stoney, well drained
soils, in frost-free areas that receive low rainfall. In South Africa
it is found only in the warm parts of the Limpopo Province.
It may however be cultivated in areas of higher rainfall provided
they are frost free and don't experience cold winters.
Derivation of name and historical aspects
The name Adansonia
was given to this tree to commemorate the French surgeon Michel
Adanson (1727-1806); the species name digitata meaning hand-like,
is in reference to the shape of the leaves.
The baobab used to belong to the family, Bombacaceae, but this is now generally regarded as a subfamily of Malvaceae. Bombacaceae is tropical with about 21 genera
and 150 species. It is host to some very interesting species. The
balsa tree, Ochroma pyramidale from South America, is well
known for its exceptionally light wood of 160kg/m2. The durian,
Durio zibenthinus, is a popular and apparently delicious
fruit from the east, which although being so tasty, has such a terrible
odour that it is banned from hotels. The silk floss tree (Chorisia
speciosa or Ceiba insignis) is a very widely planted
ornamental tree in South Africa and is a sight to behold when it
is in full bloom with its large, usually pink flowers.
The family has a number of different baobab-type trees, also of
the genus Adansonia. With one species in Australia and four
species native to Madagascar, the most spectacular, A. grandidieri,
reaches a staggering 40 m in height, only bearing branches at the
very top of the tall, thick trunk. The family is also well known
for the kapok tree, Ceiba pentandra, which is native to the
equatorial rain forests of South America, Africa and India. The
kapok tree has been widely cultivated in the tropics, for the prized
kapok fibre produced by the seed pods, which was used to stuff pillows
among other uses.
A number of significantly large, historical baobab trees can be
seen in the Limpopo Province:
- The Sagole Baobab is recorded as being the biggest tree
in South Africa with a stem diameter of 10.47 m, a height of 22
m and a crown spread of 38.2 m. It grows east of Tshipise.
- The Glencoe Baobab near Hoedspruit is probably the second
largest and bears several trunks. It has a stem diameter of 15.9
m, a height of 17 m and a crown spread of 37.05 m. This tree has
dates carved on the stem from 1893 and 1896.
- The Platland Baobab that grows near Duiwelskloof, today
houses a pub. It has a stem diameter of 10.64 m, a height of 19
m, and a crown spread of 30.2 m.
- The Buffesldrift Baobab which is in the Makopane District,
has a distinct trunk with a diameter of 7.71 m, a height of 22
m and a crown spread of 30.2 m.
Ecology
Bats primarily pollinate the large white flowers with their ruffled
petals at night, although many different insects and other creatures
such as birds will visit the sweetly scented flowers. The flowers,
being white, are more visible at night and being sweetly scented
also help to attract a wide variety of potential pollinators. The
seed capsule does not split open, instead it hangs on the tree until
it gets blown off by wind or gets collected by monkeys, baboons
or people who all enjoy the soft powdery substance that covers the
seeds. The seeds are not generally eaten by animals and are discarded,
thus effecting dispersal.
Uses and cultural aspects
Large baobab trees with hollow stems have been used by people for
centuries for various purposes including houses, prisons, pubs,
storage barns, and even as bus stops! A big tree in the old Transvaal
region is recorded as once being used as a dairy.
Another tree near Leydsdorp was used as a bar (known as the Murchison
Club) and utilized by prospectors and miners during the gold rush
of the late 19th century. One such tree in the Caprivi Strip was
converted into a toilet, complete with a flushing system.
Rainwater often collects in the clefts of the large branches, and
travelers and local people often use this valuable source of water.
It has been recorded that in some cases the centre of the tree is
purposely hollowed out to serve as a reservoir for water during
the rainy season. One such reservoir was recorded as holding 4 546
litres of water. A hole is drilled in the trunk and a plug inserted
so that water can be easily retrieved by removing the plug. The
roots of the baobab can also be tapped for water.
African honey bees (Apis mellifera) often utilize hollows
in the baobab to make their hives. One can often see a 'ladder'
of pegs hammered into the trunk which is used by seasonal honey
harvesters to gain access to the hives.
The leaves are said to be rich in vitamin C, sugars, potassium
tartrate, and calcium. They are cooked fresh as a vegetable or dried
and crushed for later use by local people. The sprout of a young
tree can be eaten like asparagus. The root of very young trees is
also reputed to be edible. The seeds are also edible and can also
be roasted for use as a coffee substitute. Caterpillars, which feed
on the leaves, are collected and eaten by African people as an important
source of protein. Wild animals eat the fallen leaves and fresh
leaves are said to be good fodder for domestic animals. The fallen
flowers are relished by wild animals and cattle alike. When the
wood is chewed, it provides vital moisture to relieve thirst, humans
as well as certain animals eat it in times of drought.
There are many legends and superstitions surrounding the baobab
tree. For example, it is believed that an elephant frightened the
maternal ancestor of the baobab. In some parts the baobab is worshipped
as a symbol of fertility. It is a belief among certain people that
spirits inhabit the flowers of the baobab and that any person who
picks a flower will be eaten by a lion. It is also believed that
water in which the seeds have been soaked will offer protection
against attack by crocodile, while sucking or eating the seeds may
attract crocodiles. It is also believed that a man who drinks an
infusion of the bark will become strong. In some areas a baby boy
should be bathed in such a bark infusion, as this will make him
strong; however, he should not be bathed for too long or he may
become obese. It is also important that this water does not touch
his head for this could cause it to swell. When inhabitants move
from one area to another they often take seeds of the baobab with
them, which they plant at their new homestead.
The bark on the lower part of the trunk often bears scars caused
by local people who harvest and pound it to retrieve the strong
fibre. The fibrous bark is used to make various useful items such
as mats and ropes, fishing nets, fishing lines, sacks as well as
clothing. Although the bark is often heavily stripped by people
and elephants, these trees do not suffer as a normal tree would
from ringbarking. Baobabs have the ability to simply continue growing
and produce a new layer of bark. The wood of the baobab is soft,
light yellow and spongy, and although it has been recorded as being
used for making boxes, this does not seem to be a widely used practice.
Many references have made mention of the exceptional vitality of
this tree, noting that even after the entire tree is cut down it
simply resprouts from the root and continues to grow; the same is
noted of trees which have been blown over in storms. Despite this
remarkable vitality, when a tree dies it collapses into a heap of
soggy, fibrous pulp. Stories exist of how such quickly decomposing
trees spontaneously combust and get completely burnt up.
More than 260 years ago baobabs were apparently successfully grown
in England and had reached heights of 5-6 m, but were all destroyed
in the heavy frosts of 1740. Surprisingly few baobabs have found
their way into cultivation, possibly due to their reputation of
being exceptionally slow growing.
The baobab was declared a protected tree under the Forest Act in
South Africa in 1941.
Determining the age of baobabs: Much speculation in literature
over many years have made certain estimates of the age of certain
large trees and their rate of growth. More recent work using carbon-dating
techniques as well as the study of core samples showing growth rings,
suggest that a tree with a diameter of 10 m may be as old as 2000
years.
Growing Adansonia digitata
Baobabs are quite easily grown from seed although they are seldom
available in nurseries. Seed can be collected from dry fruits by
cracking the fruit open and washing away the dry, powdery coating.
The dark brown to black, kidney-shaped seeds should be soaked in
a container of hot water and allowed to cool, they may then be sown
after soaking for 24 hrs. Seeds are best sown in spring and summer
in a well-drained seedling mixture containing one-third sand.
Cover the seed with sand to a depth of 4-6 mm, place the trays in
a warm semi-shaded position and water regularly until the seeds
have all germinated. Germination may take from two to six weeks.
Seedlings should be carefully monitored for damping off fungus,
which can be treated with a fungicidal drench.
Transplant the seedlings once they are 50 mm high into individual
containers, preferably in a sandy soil with some well-rotted compost
and bone meal. Baobabs grow reasonably quickly when they are young.
They will make a handsome addition to a large garden, estate, or
large parkland providing the soil is not waterlogged. Baobabs cannot
tolerate even mild frost.
When they are young, baobabs do not resemble their adult counterparts,
the stems are thin and inconspicuous, and their leaves are simple
and not divided into the five to seven lobes of the adult trees.
Saplings can be effectively grown in containers or tubs for many
years before becoming too large and requiring to be planted into
the ground. In this manner one can move them out of the cold into
a warm position in a glasshouse or indoors behind a sunny window
to prevent frost damage.
References
- Coates Palgrave, K.; P. & M. 1985. Everyone's guide to
trees of South Africa. Struik, Cape Town.
- Esterhuyse, N., Von Breitenbach, J. & Söhnge, H. 2001.
Remarkable trees of South Africa. Briza Publications, Pretoria.
- Germishuizen,G. & Meyer, N.L. (eds). 2003. Plants of
southern Africa: an annotated checklist. Strelitzia 14. National
Botanical Institute, Pretoria.
- Kubitzki, K & Bayer, C. 2003. The families and genera of vascular plants, vol. 5. Springer, Heidelberg.
- Palmer, E. & Pitman, N. 1972. Trees of southern Africa,
vol. 2. Balkema, Cape Town.
- Venter, F. & Venter, J. 1985. Making the most of indigenous
trees. Briza Publications, Pretoria.
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Author
Andrew Hankey
Witwatersrand NBG
February 2004
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