Tree rings are a layer produced by the growth of trees in a year. It appears in cross section like a wheel (or wheels) around the same wheel produced in the past. The scale ring in fish refers to the dividing line between the narrow band formed in autumn and winter and the wide band formed in spring and summer the following year. The secondary xylem produced by vascular cambium of annual rings in a growing period constitutes a growth ring. There is obvious seasonality, and only one growth ring is produced in a year, that is, the age of trees, also known as tree rings.

The longest-lived tree

A pine tree named Maichela in California, USA, is as old as 6400 years; There is also a dragon's blood tree on Canary Island in western Africa, which has lived for more than 8,000 years. Unfortunately, it was destroyed by typhoon at 1868.

The tree with the largest crown

The big banyan tree grows down from the branches and hangs "air roots". The big banyan tree around Tianma River in Xinhui County, Guangdong Province, with its crown covering about 15 mu, has become a "bird of paradise". There are more than 4,000 "air roots" on a big banyan tree in the tropical rain forest of Bangladesh, which become "column roots" after falling into the ground. The projected area of the huge canopy is as large as 1 1,000 square meters (10.5 mu), which once allowed an army of 1,000 people to escape from the scorching sun under the trees.

The tallest tree

Almond eucalyptus in Australia is generally above 100 meters, and the highest is 156 meters, which is equivalent to 50 floors, which is higher than the two "Shanghai International Hotels".