Leonardo of Pisa, a medieval mathematician, discovered the Fibonacci sequence, which is such a series; 1,2,3, that is, the number is the sum of the first two numbers. So, what is the relationship between the number series and the growth of trees? Because the new branches often need a period of body rest for their own growth and face opening before they can germinate new branches. 
a sapling grows a new branch at a certain interval, for example, one year later, the new branch still germinates the next year, and then the new branch of the current year will body rest the next year. In this way, the number of branches of a tree in each year constitutes fibonaccile.
Application of Fibonacci sequence in nature