BARK
Unlike animals, trees can’t move out of the way of danger. So how do they protect themselves?
One important way is with their bark.
Bark is like a trees’ armour. It shields the tree from hungry animals or insects, stops it from getting burnt, or drying out, when the sun is strong and gives it strength to keep standing on a windy day.
And that’s not all! Bark also contains chemical compounds which defend the tree against bacteria, fungi and insects, and help it heal when it is injured. Because of these valuable chemicals, people traditionally used bark for many things including medicine, spices, making cloth and tanning leather. The bark of almost every Kenyan tree had an important use. See the trees below for some examples.
The outside of the bark is made of dead cells. Inside this layer is the sugar pipeline, the phloem, which (like our veins) carries nutrients to all parts of the tree. An inner layer, called the cambium, produces new bark cells.
Removing tree bark hurts the tree and can even kill it. So never remove the bark yourself!
Today, scientists have developed a process called synthesis to recreate the compounds found in tree bark. So, we can benefit from the compounds that trees produce without hurting the tree.
As a tree grows, its protective armour becomes too tight. The bark begins to fall off like a snakeskin, to be replaced by new bark underneath. The different ways that bark cracks or falls off the tree can help you to tell one tree from another. When you come across a new tree, take some time to explore its bark. Look at the way it grows and cracks, feel the surface (unless it’s a hairy Nettle Tree!), take a sniff to see if it smells... Here are some different types of bark to look out for.
SMOOTH
The bark of the Shepherd's tree is smooth and pale. Light-coloured bark reflects the sun and helps keeps the tree cool. People used the bark of this tree to cure malaria.
Read more about the Shepherd's tree here
FLAKY
The bark of the Hagenia tree is flaky and a pinkish colour
The pigment which give the bark its colour also protect it from the sun. People used this bark to cure stomach aches and diarrheoa. Read more about the Hagenia tree here.
SCALY
The Camphor tree has scaly bark, which peels off in small flakes. People used this bark to cure bronchitis, headaches and stomach aches. You can read more about the Camphor tree here.
SPIKY
The East African satinwood tree is easy to recognise because its bark is so spiny! People used this bark to cure coughs, rheumatism and malaria. Read more about the Satinwood tree here.
PEELING
The colourful bark of the Commiphora tree doesn’t crack. Instead it peels off in papery strips. When the bark is damaged it produces a resin that people used to cure many illnesses. Read more about the Commiphora tree here.
CRACKED
The bark of the Umbrella thorn tree cracks as it grows. People used this bark to make fabric, dye clothes (yellow). Elephants also enjoy eating it. Read more about Acacia trees here.
HAIRY
Stinging hairs grow on the young branches of the Nettle tree. So don’t touch it! Maasai people use the bark to decorate their huts during ceremonies. Read more about the Nettle tree here.