What is a perennial plant?

   A perennial is a plant that lives longer than two years. A biennial lives two years. An annual lives one growing season.
   Woody perennials include trees and shrubs. They have stems that live for many years. Each year, a new season's growth is added and the stem increases in diameter. Most woody perennials lose only their leaves after the growing season, and evergreens retain even their leaves or needles, sometimes for three years. Herbaceous perennials have stems that die down to the ground after the growing season. Plants such as RHUBARB, LILY, ASPARAGUS, and many GRASSES live through the winter and use stored food from underground parts, such as tubers, rootstocks, and bulbs, to produce new shoots that grow the following season.