The hidden power of trees
A thick bark, graceful branches, radiant green leaves and colorful flowers, a tree is a feast for the eyes. What makes this splendor possible lies deep underground. Hidden and mostly invisible, but the foundation for almost everything that grows on sunlight: roots.
Hardworking roots
The roots of trees have an important function for the growth and health of a tree. They absorb nutrients from the soil that are essential for growth. And of course, they provide the tree with water. On a hot summer day an adult tree can evaporate more than 200 liters of water. How does a tree get all that water pushed up against gravity? The answer is twofold. From below, the absorption of minerals leads to a higher osmotic value and 'root pressure' arises upwards. From above, evaporation of water from the leaves creates a suction effect. With these two forces, trees such as the Sequoia and Eucalyptus can transport water more than 100 meters upwards.
Who has the longest?
Unlike animals, a tree grows as long as it lives. The tallest living tree (as far as known) is a Sequoia Sempervirens of 115 meters high [1]. But what about underground? Trees can vary in size and shape below ground as much as they do above ground. This is beautifully made visible by Prof. Erwin Lichtenegger (affiliated with the Plant Sociological Institute in Klagenfurt) and colleagues, who made over 1000 drawings of excavated root systems over a period of 40 years [2].
A height of 115 meters is already impressive. But underground, that length is surpassed with playful ease. The tree with the deepest roots in the world is a fig tree in the Echo Caves of South Africa. This tree has roots of 400 meters (!) deep [3]. That is more than the Eiffel Tower, including its foundation.
Root power
If you've ever had to pull a tree out of the ground, you know how powerful roots can be. They anchor themselves with many underground branches and are soon impossible to get loose with a shovel. In your own garden it may sometimes be difficult, but the strength of roots is of great importance for nature. On the one hand they can erode rocks with which they release minerals and on the other hand they can prevent erosion of loose soil.
We also became acquainted with the power of roots in Treemore's experimental garden. The fleshy roots of this Bird of Paradise flower (Strelitzia reginae Mandela's gold) could not be locked up and broke open the letterbox pot with ease.
Root speech
The power of roots has not gone unnoticed. The symbolism of roots has been given a prominent place in language. How about I’m rooting for you (supporting someone with a challenge), back to your roots (to return to where you came from) and being rooted in something (being strongly influenced by), for example. In addition to proverbs, there are many more quotes with a starring role for roots. One of the most beautiful, to conclude, comes from philosopher and Nobel laureate Bertrand Russell: Love should be a tree whose roots are deep in the earth, but whose branches extend into heaven.