A tree is a wooden stick trying hard to reach the sky. It wants to reach the sunlight which it needs for life. The stick is called a trunk. Raising itself tall also keeps the leaves farther away from insects and animals. There are two main types of trees: conifers and broad-leaved.
Broad-leaved trees are usually rounded. Conifers grow into a triangular shape. To be called a tree the plant must be over twenty feet tall. It can have only one trunk. Anything else is a shrub. A tree below twenty feet is called a sapling. Redwoods are the tallest trees in the world. They can grow to more than three hundred-sixty feet in height.
All the parts of a tree work together to make it grow. Leaves make food by using sunlight and gases in the air. The roots take water and minerals from the soil. The leaves need water, and the roots need food. The trunk carries water and sap up and down the tree. Sap is the name for the tree's food. The water and sap channels are just under the outer layer of bark. The bark protects them. As a tree grows, the bark cracks open on the outside. New bark grows on the inside.
The leaves of broad-leaved trees are thin, flat, and often wide. In northern climates, broad-leaved trees are usually deciduous. They lose their leaves in the fall. The veins in a leaf carry food and water around the leaf. A leaf's shape can identify the type of tree. Young leaves are especially tasty to deer and other animals. Some trees have thorns to keep the eaters away.
Conifers are trees which produce cones. Some conifers have hard, spiky needles. Leaf-eating animals cannot eat these spikes or needles. Others have bad-tasting leathery leaves or scales. Each needle of a conifer stays on the tree for three to four years. They save their energy by not having to make new needles each year.
Twigs stick out from trees and are the growing ends of the tree. Each twig has some buds. These contain new shoots. The shoots open and become new twigs. Sticky scales protect the buds from insects.
Some trees have beautiful blossoms. These attract bees or other insects. They then carry pollen from male flowers to female flowers. Female flowers make seeds from the pollen. These may grow into trees. On conifers the cones serve as blossoms. Male cones produce pollen. This is blown to the female cones. Seeds begin to grow. The cone scales harden and protect the seeds. Seeds fall from cones to grow into new trees. They have light wing-type propellers on them to blow them away from the parent tree. They could not get sunlight under the tree.
Some trees use their fruit as a means of spreading seeds. They may rely on the animals who eat the fruit and then leave the seeds in their droppings. These may contain seeds which will grow into new trees. Other trees have a tasty seed or nut. Many of these are eaten by animals. The ones which are not may grow into trees.
In summary, a stick with leaves or needles on it is called a tree. The tree has to continually stretch to the sky to find the life-giving sun it needs to grow. Its height also keeps animals and insects away from the leaves. Conifers and broad-leaved are the two main types of trees.