Plants are among the most widely diverse group of living things on earth. They range from simple, tiny plants, such as duckweed, to huge and imposing redwood trees reaching hundreds of feet in the air. Though all very different in appearance, they share many similarities in their anatomy. Most plants possess roots, stems, leaves, flowers and fruits in one form or another.
Roots are plant organs that absorb water and nutrients, anchor the plant to the substrate it is growing in or on, and support the stem. Roots usually grow underground, however some plant species have roots that grow in water or are exposed to air.
Roots tend to be either filamentous and multi-branching, or in the form of a single larger root called a taproot. A carrot is an example of a taproot. Some roots, such as a potato, can also store food for the plant. Roots develop tiny hairs that are capable of absorbing water and chemical nutrients directly from the soil.
The stem is the main above-ground structure of the plant and is responsible for providing the form of the plant. They can vary from simple, thin stems on grasses to thick, sturdy trunks of large trees. They are highly vascularized and provide a means to move water and nutrients throughout the plant.
Stems act at support for buds, leaves, flowers and fruit. Nodes are locations on stems where buds form. These are the juvenile form of leaves and flowers.
Leaves sprout from stems and provide the ability to convert nutrients and water into sugars that are, in turn, used as energy for the continued growth of the plant through a process known as photosynthesis. Leaves also contain specialized organs that provide for the intake of carbon dioxide, which is essential to the process. These same organs give off oxygen as a by-product.
Leaves come in a wide range of forms from tiny, thin pine needles, to the huge fronds of the raffia palm, which can reach up to 25 meters long.
Flowers are the reproductive organs of a plant that eventually produce seeds. Flowers can be male or female, or may possess both at the same time. The male portion of the plant produces sperm in the form of pollen that will fertilize the ovaries of the plant. This union will result in the production of seeds, which will propagate the species.
Flowers range in a wide variety of sizes, colors and shapes. Many are colorful and fragrant. Flowers are often pollinated by insects or other animals. Still others require wind or water to achieve pollination.
Fruits are the seed-bearing growths that are the result of seed production. Fruits may be simple in form, developing from a single ripened plant ovary (such as a peach, plum, apple or orange) or the ovaries may be aggregated, as with strawberries or blackberries.
Seeds range from almost microscopic size--as with some species of orchids--up to huge pumpkins that are specially grown for size and can range up to over 1,000 pounds. Many fruits are edible and are eaten as either true fruits or vegetables, such as tomatoes or cucumbers.