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A perennial plant or simply perennial is a plant that lives for more than two years. The term is often used to differentiate a plant from shorter-lived annuals and biennials.
Biennial are plants whose lifecycle spans two years, so they flower and produce seeds in their second year. A familiar biennial is foxglove, Digitalis purpurea. Some plants grown as biennials are, botanically speaking, short-lived perennials, for example, sweet william and wallflower.ardy annuals are plants that go through their entire life cycle in one season and that can be sown outside in the open garden in spring where it is to flower, for example, Centaurea cyanus â cornflower.