Plants are on of the five kingdoms into which all living things are divided by scientists, the other four being animals, fungi, protists, and monerans.
A typical plant is made up of four main parts. These are (1) roots, (2) stems, (3) leaves, and (4) flowers. The roots, stems, and leaves are called the vegetative parts of a plant. The flowers, which includes fruit, and seeds are known as the reproductive parts.
Most roots grow underground, and absorb from the soil absorb the water and minerals that the plant needs to grow. The roots of some plants float freely in water or attach themselves to tree branches.
Roots also anchor the plant in the soil. The roots of some plants such as beets, carrots, radishes and sweet potatoes also store food for the rest of the plant to use.
Stems include the trunk, branches, and twigs and make up the largest parts of some kinds of plants, particularly the common trees. Other plants, such as cabbage and lettuce, have such short stems that they appear to have no stems at all. The stems of some other plants like potatoes, grow partly underground.
Most stems grow upright and support the leaves and reproductive organs of plants, holding these parts up in position where they can receive sunlight.
Leaves differ greatly in size and shape. The largest leaves are those of the raffia palm, which grow up to 20 metres long and 2.5 metres wide. Most plants have broad, flat leaves with smooth edges. Edges of leaves of some plants are toothed or wavy. A few kinds of leaves, such as those of pine trees and cactuses, are rounded and have sharp ends.
Leaves make food needed by plants the food by a process called photosynthesis. In this process, chlorophyll in the leaves absorbs light energy from the sun, which is used to combine water and minerals from the soil with carbon dioxide from the air. A network of veins carry water with minerals to the food-producing areas of a leaf. The veins also help support the leaf and hold its surface up to the sun.
Flowers form the reproductive parts of flowering plants. Most flowers have four main parts - calyx, corolla, stamens, and pistils. The flower parts are attached to a place on the stem called the receptacle.
The calyx consists of small, usually green leaf like structures called sepals. All the petals of a flower make up the corolla. The stamens and the pistils are attached to the receptacle inside the sepals and the petals. Each stamen has an enlarged part called an anther that grows on the end of a long, narrow stalk called the filament. Pollen grains are produced in the anther. The pistils of most flowers have three main parts: (1) a flattened structure called the stigma at the top, (2) a slender tube called the style in the middle, and (3) a round base called the ovary. The ovary contains one or more structures called ovules. Egg cells form within the ovules. The ovules become seeds when sperm cells fertilize the egg cells to begin the formation of seeds and fruit.
