Perennial
In botany, a perennial plant or simply perennial is a plant that lives more than two years.[1] The term (per- + -ennial, "through the years") 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 (secondary growth in girth) from trees and shrubs, which are also technically perennials.[2] Notably, it is estimated that 94% of plant species fall under the category of perennials, underscoring the prevalence of plants with lifespans exceeding two years in the botanical world.[3]
Perennials—especially small flowering plants—that grow and bloom over the spring and summer, die back every autumn and winter, and then return in the spring from their rootstock or other overwintering structure, are known as herbaceous perennials.[4] However, depending on the rigours of the local climate (temperature, moisture, organic content in the soil, microorganisms), a plant that is a perennial in its native habitat, or in a milder garden, may be treated by a gardener as an annual and planted out every year, from seed, from cuttings, or from divisions. Tomato vines, for example, live several years in their natural tropical/subtropical habitat but are grown as annuals in temperate regions because their above-ground biomass does not survive the winter.
There is also a class of evergreen perennials which lack woody stems, such as Bergenia which retain a mantle of leaves throughout the year. An intermediate class of plants is known as subshrubs, which retain a vestigial woody structure in winter, e.g. Penstemon.
The symbol for a perennial plant, based on Species Plantarum by Linnaeus, is 
, which is also the astronomical symbol for the planet Jupiter.[5]
Perennial plants can be short-lived (only a few years) or long-lived. They include a wide assortment of plant groups from non-flowering plants like ferns and liverworts to the highly diverse flowering plants like orchids, grasses, and woody plants. Plants that flower and fruit only once and then die are termed monocarpic or semelparous; these species may live for many years before they flower.[6] For example, century plant can live for 80 years and grow 30 meters tall before flowering and dying.[7] However, most perennials are polycarpic (or iteroparous), flowering over many seasons in their lifetime.[8] Perennials invest more resources than annuals into roots, crowns, and other structures that allow them to live from one year to the next. They often have a competitive advantage because they can commence their growth and leaf out earlier in the growing season, and can grow taller than annuals, in doing so they can better compete for space and collect more light.[9]
Perennials typically grow structures that allow them to adapt to living from one year to the next through a form of vegetative reproduction rather than seeding. These structures include bulbs, tubers, woody crowns, rhizomes, turions, woody stems, or crowns which allows them to survive periods of dormancy over cold or dry seasons; these structures typically store carbohydrates which are used once the dormancy period is over and new growth begins.[10] In climates that are warm all year long, perennials may grow continuously.[11] Annuals which complete their life cycle in one growing season, in contrast with perennials, produce seeds as the next generation and die;[12] the seeds may survive cold or dry periods or germinate soon after dispersal depending on the climate.