It is a plant that lives for more than two years.The term is often used to differentiate a plant from shorter-lived annuals and biennia. A perennial plant or simply perennial is a plant that lives for more than two years.
Perennials can be divided into two categories. Deciduous perennials, such as the perennial flowers mentioned above, grow part of the year and fall dormant the rest of the year. Evergreen perennials, such as pine trees, grow year round. Some people have a hard time remembering the proper term for each type of plant. That’s because some of them are annual plants and some are perennial plants. Annual plants are plants with a life cycle that lasts only one year. They grow from seed, bloom, produce seeds and die in one growing season. They then need to be replanted each spring. Perennial Seeds and Plants. something to look forward to... Year after year, Burpee's perennial seeds and plants will fill your home garden beds and borders. Select from our full palette of colors, textures, forms and fragrances to create the perennial garden of your dreams-a sensory pleasure for years to come.  Perennials, or plants and flowers that come back year after year, are found in virtually every yard. Perennial flowers work in multiple situations: in whole garden beds, in combination with annuals and bulbs, as accent to shrubs and trees, and in containers and windowboxes. Perennial. Asters get their name from the Latin word for star, and their flowers are indeed the superstars of the fall garden. Some types of this native plant can reach up to 6 feet with flowers in white and pinks but also, perhaps most strikingly, in rich purples and showy lavenders. Perennial plants can be short-lived (only a few years) or they can be long-lived, as are some woody plants like trees. They include a wide assortment of plant groups from ferns and liverworts to the highly diverse flowering plants like orchids and grasses. The symbol for a perennial plant, based on Species Plantarum by Linnaeus, is, which is also the astronomical symbol for the planet Jupiter. Not all plants with the ability to be perennial are hardy in all areas. Some can be killed by freezing temperatures, excessively dry conditions or other growing conditions. This is why hardiness zones are so important. Knowing what zone you garden in will allow you to determine what plants will survive in your area. The term perennial is most often used for plants with showy flowers, but plants like ornamental grasses, tropicals and other plants that have their own categories may also be perennial.  The term  perennial  refers to herbaceous (“green”) plants since woody plants, such as trees, are perennial by definition. Unlike annuals, perennials tend to bloom for just a short time — one to three weeks — each year. Examples of popular perennial flowers include tulips, asters, black-eyed susans and lilies. That’s because some of them are annual plants and some are perennial plants. Annual plants are plants with a life cycle that lasts only one year. They grow from seed, bloom, produce seeds and die in one growing season. They then need to be replanted each spring. Definition of Perennial Plants. Simply put, unlike annuals or biennials, perennials are plants that live year after year. Some perennials, such as trees and shrubs, have significant life spans. Others, like many flowering perennials, may need to be replaced every three or more years. If you are ruminating on what to plant in your garden, re-landscaping or adding to the home landscape, you may be considering any number of perennial garden plants. 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. The term is also widely used to distinguish plants with little or no woody growth from trees and shrubs, which are also technically perennials. The symbol for a perennial plant, based on Species Plantarum by Linnaeus, is, which is also the astronomical symbol for the planet Jupiter. Perennials are the plants that keep on giving. When properly planted and taken care of, these plants and flowers can be counted on to come back in bloom year after year saving you time, energy and money. 
http://wonderopolis.org/wonder/whats-the-difference-between-annuals-and-perennials/ http://www.burpee.com/perennials/ http://www.bhg.com/gardening/plant-dictionary/perennial/ https://en.wikipedia.org/wiki/Perennial_plant http://gardening.about.com/od/perennials/g/Perennial.htm http://wonderopolis.org/wonder/whats-the-difference-between-annuals-and-perennials/ http://www.gardeningknowhow.com/garden-how-to/info/perennial-garden-plants.htm https://en.wikipedia.org/wiki/Perennial_plant http://www.homedepot.com/b/Outdoors-Garden-Center-Garden-Plants-Flowers-Perennials/N-5yc1vZc8ry
what is a perennial plants