The plant kingdom provides beauty, protection, food and shelter to all corners of the earth. More than 250,000 species of plants exist, helping to sustain life as we know it. Trees, vines and shrubs provide habitats and nutrition to animals and insects. Vegetables and fruits provide nutrition for the human population. Flowers and other ornamental plants offer beauty that allows us to marvel at nature's power and to create our own aesthetically pleasing gardens.
Types of Plants
The plant kingdom offers many types of plants, including annuals, biennials, perennials, shrubs, vines, trees, herbs, flowers and vegetables.
While each plant differs in appearance and purpose, several structural elements are common in all. Reproduction occurs through seeds, spores and bulbs, including rhizomes, corms and tubers. After germination, root and shoot systems appear that build the basic structure of a plant.
Starting from Seed
The life of a plant begins beneath the soil, once a seed has been planted. The seed, containing the embryo and one (monocot) or two (dicot) cotyledons, takes in moisture and nutrients from the soil. Once the seed casing has reached full capacity, it cracks open to reveal the root and shoot systems.
During germination, the shoot system reaches upward, searching for light and heat, in order to begin growth through photosynthesis. The main root (radicle) pushes downward in search of more nutrients and moisture that it will need to form the root system that will support the vegetation above. Depending upon the type of plant, germination can take from five to 30 days.
After germination, the plant begins to develop its vegetation, or foliage. This includes the stem, branches, leaves and buds. As this development progresses the buds will begin to form blooms, which are needed for fertilization of the plant. Some plants are self-fertilizing (containing both male and female parts), while others need assistance through nature or humans, in order to pollinate properly.
Pollination occurs when the pollen is released from the male anthers and delivered to the female carpel of the bloom. Wind, flying insects or gentle vibration of the plant are all involved in helping a plant to pollinate. Once pollination is complete, the bloom dies off and, for plants that produce flowers, vegetables or fruits, the production cycle begins.
As a plant reaches maturity the fruit, vegetable or flower forms, grows and either opens to reveal a flower or produce a fruit or vegetable. For trees and shrubs, the plant simply continues to grow buds to sustain life and seed pods for further propagation.
The final stage of plant life is death. Depending upon the type of plant, this can be from one growing season to more than a century. Natural forces such as storms, insect and rodent infestation and disease can cause early demise. For annual vegetables, fruits and flowers, the final cycle begins after harvest of all viable produce and the onset of colder weather. For biennials and perennials, the vegetation dies off and seeds or bulbs move into a dormant phase awaiting the next growing season. Trees and shrubs shed leaves and seed pods and move into dormancy to survive cold temperatures.