So I know that “decide” isn’t really the right word, but plants very clearly respond to their environment in a way that is dynamic. They can determine which side of the tree is getting more sun, and put more leaves there. they can determine where there tends to be more water in the soil, and grow more roots in that direction.
Since they don’t have what we would call a nervous system, how is this information processed? There seems to be clear research into the electrical signals moving through the Phloem, but where do these get “processed” in a way that the organism as a whole can make “decisions”?
In: Biology
Living cells are full of molecular machinery. They use hormones and amino acids and chemical concentration gradients to communicate and think. Even the source code is stored as a molecule.
A bark cell will produce a certain chemical when its getting light. The chemical takes several days to break down, so the light levels are averaged accross the whole day. If enough cells in an area produce enough of this hormone, one of them will start making a new branch. The new branch eats up all the hormone, to prevent the tree from growing too many branches close together. A new branch has a certain pattern that it follows, which includes leaves. The leaves block light from reaching the bark, preventing it from making more branch hormone.
When a new branch starts to populate itself with leaves, it starts using more water. The extra demand for water puts more stress on the roots, which causes more rooting hormone to be produced. Roots can sense water – they grow lots of little tendrils in every direction, and whichever tendril finds the most water will grow the most. This makes the roots seem like they’re intelligently growing towards the water, but really they’re just following the smell of water.
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