Despite seeing trees all around us, there are a few misunderstandings which exist about how they actually grow. Taking the time to study how real trees grow can teach us about the surprising mechanisms that these complex plants boast.
A Look at Plumbing
We can view trees like annual plants. Each of them growing at each end of a large, interconnecting plumbing system. The plants can be referred to as twigs. The twigs create fruit, flowers and leaves of a tree. Looking at them by themselves, they are very similar to other plants. However, it is how they connect to the larger system of branches that makes them different. The branching system is responsible for the distribution of water, sugar and hormones which work together to make the twigs – this keeps growth regulated and allows the tree to become the incredible structure we gaze in awe at.
A Look at the Water Flow
Older branches only have a thin outer layer beneath the bark which is a living tissue. The remainder of the branch is simply dead cells. The cell walls of these cells give the tree structure and strength to be able to stand tall. However, of more importance is the sponge like structure which is able to draw water from the roots upwards and into each branch and then each leaf.
Water is used by a tree in several ways. Water, which is drawn upwards through the branches, is filtered to make use of all the minerals and nutrients. Using the heat of the sun, each leaf evaporates water to aid a steady flow of nutrient-rich water. This dries the sponge out and encourages it to draw more water from the soil.
A Look at the Flow of Sugar
As well as water evaporation, leaves use water for photosynthesis. This moves us on to sugar flow. Leaves absorb energy from the sun and bind carbon dioxide with water to make sugar molecules. These sugars are used as an energy store by the tree as a whole. This sugar flow takes place in the living tissue of the branches, that being the thin layer found below the bark. The leaves keep topping this up, then the cells in need make use of it. The buds, branches, trunk and root are all connected.
A Look at the Flow of Hormones
The water flow and the sugar flow also distribute hormones. For example the apical meristems, the branch tips that form new cells, produce the hormone Auxin. This is used for growth regulation. It is this hormone that sends a message to lower branches to stay low.
A Look at the Twigs
We now understand how trees regulate their growth in the bigger picture. Now let’s look at the twigs. Twigs take their orders from the hormones moving through the plumbing system, however, they are individualistic in nature. A twig’s life starts in the bud.
At the base of each leaf found at the end of each branch is a bud. Within the bud is the embryonic beginnings of a twig, protected in a cocoon to give it the ability to survive the winter.
A Look at the Senses
Each year numerous twigs grow from the buds. Twigs are like the eyes and ears of the tree. Granted trees can’t actually hear, nevertheless, they have all the senses that animals have. Twigs use these senses to decide where to grow.
It is the tree’s sense of balance that allows it to grow against gravity. Biologists use the term gravitropism to describe the process. It means that the tree grows up, while the roots grow down.
Light and food are crucial to a tree. This makes it understandable why trees have developed a more superior sense for light. A twig can pick up on many hues of light. When a twig can’t see much light, it begins to grow rapidly in attempt to find more.