Positive feedback
Once you start looking, you find feedbacks all over the place. These are loops where one thing effects another thing which then effects the first thing back again. So it goes round and round in a loop ... forever .. or at least until something butts in and stops them.
They can be "positive" or "negative" but most things in the real world are made of complicated combinations of both.
Feedbacks
Little plants might only have a couple of tiny leaves to start with, but as they grow more, they capture more sunlight which they can use to grow more leaves to capture more sunlight. This way they grow faster and faster as they get bigger. That's a positive feedback. Positive feedbacks are good at making things happen quickly.
But after a while, they're so big that they start shading out lots of their own leaves, slowing themselves down again until they're as big as they can possibly get. That's a negative feedback. Negative feedbacks are good at finding balance and equilibrium.
This way, through a basic combination of feedbacks, plants become grown-up plants.
Why this is so interesting
Grown-up plants don't just stop. They're still capturing loads of light and going like the clappers, it's just that negative feedbacks are holding everything in balance, so it just looks like they've stopped. Underneath, their positive feedbacks are poised like panthers, ready to leap into action as soon as anything changes, and their negative feedbacks are ready to calm things down again as soon as some change has occurred.
It's not just plants that do this. It's what produces those shapes you find everywhere and on almost any scale you care to look.
