Many vascular plants in which flower parts mature after fertilization into seed-bearing fruit is considered an angiosperm, or flowering plant. Flowering plants first appeared about 145 million years ago and today represent more than 80 percent of all green plants. Directly or indirectly, they represent the major source of food for all the animal species on Earth. From insects to humans. Flowering plants also supply raw materials for clothing such as cotton and linen. A large number of drugs and remedies, and important building materials. The flowering plants in our gardens and homes also add priceless aesthetic pleasure to our lives. Angiosperms come in two basic forms: woody and herbaceous.
Trees and shrubs represent the woody forms. Herbaceous plants, which include many more species than we normally think of as herbs, are categorized as annuals, biennials, and perennials. Annuals complete their whole growth cycle in one season. Biennials use the first year to grow from seed. And the second to develop flowers and fruit for the next generation. Perennials grow for many years and often produce flowers every year.
While they may die back in winter, perennials produce new shoots each growing season from underground structures such as bulbs, rhizomes, corms, and tubers. Pollination—The transfer of male reproductive cells to the female reproductive parts of a plant of the same species-occurs by a number of methods. Some random and some more orchestrated. Some flowers require pollinators—mostly insects, but also birds, reptiles, and mammals—that transport the pollen to other plants of the same species. These flowers often entice with the strong scent and even landing guides on their petals. The pollinator’s reward is the nutritious pollen itself or nectar, a sweet liquid produced in the flowers.