Virtually everywhere on earth flowers blossom on plants and trees. They are essential for reproduction of vegetation, since they develop the seeds for further growth, and flowering plants are the nutrient source for almost all species of animals. Humans consume grains, fruits and vegetables, and the animals many people use for food, such as cattle, hogs and sheep, also live on flowering plants.

Any plant that produces some sort of flower, even a small colorless one, is a flowering plant. Thus, grasses, roses, apple trees, lilacs and oaks are all flowering plants. At least 200,000 kinds of flowers have been classified, from the microscopic water blossom to the three-foot-wide tropical plant called the Giant Rafflesia. A blossom's shape may be long and thin, such as grass, or flowers that resemble stars, balloons or even insects. Flowering plants also may have pleasant fragrances to attract the birds and insects that...