Plants and flowers that have a life cycle of three or more years, and are present during all seasons of the year. Types of perennials include woody plants, such as trees and shrubs, as well as, small flowering plants. Perennials flourish in warm spring and summer seasons and die back in the autumn and winter due to their hardy root stock as opposed to seeding. If proper yard care is used, perennial plants can live indefinitely in moderate climates; they require diligent lawn and shrub care if they are to perpetuate.