Plant species means a grouping of related organisms constituting a systematic unit, occupying a certain permanent and relatively constant place in nature and fulfilling its functions in the universal biological metabolism in the manner specific only for the grouping.
Trees
Trees are big and tall plants. They have very thick, woody and hard stems called the trunk. This single main stem or the trunk gives rise to many branches that bear leaves, flowers and fruits. Some trees are branchless like coconut trees; i.e., they have only one main stem which bears leaves, flowers, and fruits all by itself. The lifespan of a tree is very long. i.e., for several years. Banyan, mango, neem, cashew, teak and oak are some examples of trees.
Herbs
Herbs are short-sized plants with soft, green, delicate stems without woody tissues. They complete their life cycle within one or two seasons. Generally, they have few branches or are branchless. These can be easily uprooted from the soil. Herbs contain enough nutritional benefits, including vitamins and minerals, to make them a part of a healthy balanced diet. Tomato, wheat, paddy, grass and bananas are a few examples of herbs.
Shrubs
Shrubs are medium-sized, woody plants taller than herbs and shorter than a tree. Their height usually ranges from 6m to 10m tall. Their features include bushy, hard, and woody stems with many branches. Although stems are hard, they are flexible but not fragile. The lifespan of these plants usually depends on the species. Rose, jasmine, lemon, tulsi, and henna are some of the common shrubs around us.
In addition to these three categories of plants, there are two more types which need some support to grow. They are specifically called climbers and creepers.