1, interpretation

Trunk is an important part of trees. Trunk has wooden characteristics and is often used in furniture manufacturing and building materials.

2. Source

Yang Shuo's Equatorial Snow: "All I can know is Mubu Yushu, whose trunk is so thick that more than a dozen people can't even hold their arms."

3, the composition of the trunk

Trunk * * * is divided into five layers:

The first layer is bark. Bark is the surface layer of the trunk, which can protect trees and prevent the invasion of diseases.

The second layer is phloem. This fibrous tissue carries sugar from the leaves.

The third layer is the cambium. This layer is very thin and is the growth part of the trunk. All other cells come from this layer.

The fourth layer is sapwood. This layer transports water from the roots to all parts of the tree. This layer is usually lighter than heartwood.

The fifth layer is heartwood. Heartwood is an old sapwood called xylem. Most trunks are heartwood.

Backbone example:

1. Before climbing the tree, I had a rest and refreshed myself. Then, I suddenly stood up and jumped up, grabbing a branch of the tree with one hand. Then, I lifted the trunk and climbed up slowly. Later, I felt exhausted, so I came down.

2. People ignore tiny water droplets, but have you ever thought about the perseverance that water droplets can penetrate stones! People ignore the weak ants, but have you ever thought that the collective is the unity of strength! People ignore the old trunk, but have you ever thought about the perseverance of standing for thousands of years! Tiny makes life more exciting.

The trunk of the apple tree is covered with dry moss, and the jagged bare branches are dotted with a few red and green leaves, which bend into the air like an old man's elbow.

In the late autumn evening, I walked in the quiet campus, only to see the flowers withered, the leaves withered, the bare branches drooped listlessly on the trunk, and the green grass in the past was only yellow now.