1, evergreen tree with straight trunk and height of 30 ~ 36 meters.

2. The bark is grayish brown, and the longitudinal crack is scaly and flaking.

3. Winter buds are cylindrical, reddish brown, thick and resin-free.

4. Needles with two or three needles in a bundle are18 ~ 30 cm long, dark green, with stomatal lines on both sides of the ventral back and fine serrations on the edges.

Flowering in May, March and April. In the following year10 ~11month, the fruit is ripe, and the cones are oblong and conical, with 2 ~ 3 aggregates.

6. The seeds are oval and triangular.

Composition of the tree:

The four main parts of a tree are roots, trunks, branches and leaves. Roots are underground, and there are many roots at the bottom of a tree.

The trunk is divided into five layers.

The first layer is bark. Bark is the surface layer of the trunk, which can protect the tree and prevent the invasion of diseases. Below the bark is phloem, which transports sugar from the leaves. The third layer is cambium, which is very thin and is the growth part of the trunk. All other cells come from this layer.

The fourth layer is sapwood, which transports water from the roots to all parts of the tree. This layer is usually lighter than heartwood. The fifth layer is heartwood, and heartwood is old sapwood, both of which are called xylem. Most of the trunks are heartwood. When a tree grows up, its roots will firmly entangle the soil under its body to prevent soil erosion.

Extended data:

The role of the tree:

1, trees can maintain ecological balance.

Because trees can inhale carbon dioxide and exhale oxygen through photosynthesis, they can make the air fresher and cleaner. According to the survey, the oxygen released by an acre of forest can be used for 65 people to breathe. Trees and our human existence are closely related and inseparable.

2. Trees can prevent wind and fix sand.

Because the roots of trees need to be consolidated, they can inhale a lot of dust and conserve water and soil at the same time. One acre of forest can inhale 20-60 tons of dust every year. In our daily life, it is very common for people to cut valves indiscriminately, so some places have also caused floods, the main reason is that they have lost the protection of trees.

3. Other functions

There is no doubt that trees can also reduce noise pollution, and 40-meter-wide forest belts can reduce noise10-15 decibels; Secretions from trees can also kill bacteria. Generally, there are 30,000 to 40,000 bacteria per square meter in open space, while there are only 300 to 400 bacteria in forest. In addition, big trees can reduce the temperature and increase the humidity.

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