Behind the exteriors of the world’s trees there beats the heart of a superhero.
Among the largest and oldest living organisms on the planet, trees are able to warn one another of approaching danger and mount a defence. In certain cases, they are able to send their armies to fight off attackers and use complicated strategies to ensure that following generations have their roots in fertile ground and their crowns in the clean blue sky.
The trees that can be spotted along the Zambezi River and on our private Katombora Island have very interesting tricks of their own that help them to survive in a wild world – from the 23 or so baobabs and 200 year old Jackalberry near Island Lodge to the weird and wonderful knob thorns, python creepers and waterberries you’ll see too.
In Lesson 7 of the Royal Chundu Homeschool, let’s look at some of these icons ~ at what makes them worth getting to know and understand, while you breathe in their beauty from below. We’d love you to share pictures of trees that really amaze you! Beautiful or complex, peculiar or simple… trees you’ve seen on trips or at home. Post your photos on social media and tag us #royalchunduhomeschool @royalchundu with one fascinating fact / what you like most about them!
The upside-down tree, when its branches are bare and looking like roots sticking up into the air, has the power to live forever. Well, maybe not actually forever, but the baobab tree can live for thousands of years – which in human terms is forever. Baobabs have soft, fleshy trunks and are a favourite dry season water source for elephants. They can, however, survive these attacks from the largest land animal in the world, survive and grow back bigger and stronger.
The Knob Thorn
Knob thorns (Senegalia nigrescens) are typical acacia trees, covered in thorns that could rip and poke an unwary grazer. The thorns and knobs on the branches and trunk are a defence against elephant and kudu. But the sly acacia has an arrangement with certain animals.
As vervet monkeys, baboons and giraffes feed on the flowers, their faces are covered in yellow pollen which they then transfer to all the trees that they visit and so are major pollinators of the knob thorn tree. An eat-as-much-as-you-can buffet reward for work well done.
Knob thorns are slow-growing trees which results in a hard, fire and termite resistant wood.
The Fever Tree
Photosynthesis is conventionally carried out in the leaves of plants, however, the fever tree is one of the few tree species on earth whose bark performs this process as well as its leaves. This double dose of sun-power allows the fever tree to grow extremely rapidly. The fever tree’s scientific name is ‘Vachellia xanthophloea’ and refers to the tree’s distinctive greenish-yellow magic bark. The bark is often covered with a fine yellow dust.
The fever tree has had a chequered history, accused by early European settlers of causing malaria because it shared a liking for low-lying and swampy ground with mosquitoes. It has since been cleared of these charges. Unfortunately, it was not so lucky in its fight with officialdom. In 2011, all African acacias were stripped of their titles and reclassified as either vachellia or senegalia. So remember, next time someone mentions an acacia growing in the shadow of Mount Kilamanjaro or on the banks of the Zambezi, they are mistaken because acacias are now Australian.
Unlikely as it sounds, the fever tree does have friends. Ants often nest in dead and rotting areas of the tree and will attack any animal that disturbs them. Elephants are wary of ants and so this helps to keep them at a distance.
Another defensive strategy of ‘acacias’ is the release of tannins. When the trees ‘feel’ nibbling teeth they release tannins to deter browsers like kudu, giraffe and elephant and emit ethylene into the air which warns other trees of the impending danger. These then produce their own leaf tannin within just five to ten minutes.
They’re either very clever or pretty dumb, these Jackalberry trees. They often grow on termite mounds, seemingly unaware that the diet of termites is almost exclusively wood. But there is a method in their apparent madness. African soils are often hard, sun-baked and impervious to the rainstorms that quickly pass. Termites aerate the soil allowing the rain to seep in and this, along with their nitrogen and phosphorous-rich droppings, creates moist and highly fertile ground. Just the kind of place a tree fancies, the perfect tree nursery if it wasn’t for all those snapping jaws. Luckily, the slow-growing Jackalberry timber is extremely hard. Besides, termites don’t eat healthy, living wood. So it turns out that living in the most dangerous place on earth, for a tree, is a good idea after all.
It seems that everything and everyone, except termites, likes to take a bite out of the Jackalberry tree or, at least, its fruit. The Jackalberry tree got its name from the fondness jackals have for the fruit. Maybe some naming-consultant spotted one indulging in a fruity snack and thought of the obvious name.
The waterberry tree is a real hero. It supplies sweet (when ripe) plum-coloured fruit that is eaten by children, monkeys, bush-babies and birds. It offers shade and shelter for bushbuck and duiker. Ones overhanging the Zambezi River provide perches for the kingfishers, herons and fish eagles. Known locally in Zambia as the musombo tree, a concoction of dried and/or boiled roots and leaves is used as a traditional medicine for the treatment of respiratory ailments, such as coughs and tuberculosis. If taken internally, they treat stomach disorders like indigestion and diarrhoea and the roots help ease giddiness. Applied topically it speeds up wound healing.
Trees are our protectors.
In their living forms they provide homes and shelter to millions of living creatures and by absorbing carbon dioxide they are major protagonists in the war on climate change. Even when dead they continue to warm, feed and house us. But remember, they are not defenseless.
Now, make a list of the super-powers of your favourite super-heroes, trees!