There are approximately 20,000 species of tree . These trees vary between forest trees and ornamental trees strong fragile . The trees grow more diverse formations in the humid tropics . Divides scientists interested in plant studies , plants with similar qualities to different groups see the plant. And botanists collecting all kind of trees with other plants have common traits with these trees . Therefore, we find that a group of these plants include some trees and some shrubs or plants Almaatarhh and some herbaceous plants . For example , we find that the false acacia trees and plants broom brooms and alfalfa , all belong to one species , these plants have been collected in one group ; because they reproduce in the same way and have similar flowers . On the other hand , we find that some similar trees , such as tree ferns and palm trees belong to different groups of plants.
The trees can also be split into six groups , according to different qualities in common . These six groups are: 1 - broad-leaved trees . 2 - needle -leaved trees ( conical ) . 3 - palm trees and Alcave and tulips . 4 - Alsecassih trees . 5 - tree ferns . 6 - ginkgo trees