Perennials

A perennial plant or perennial (Latin per, "through", annus, "year") is a plant that lives for more than two years. Herbaceous perennials are plants that do not form woody tissue and the term perennial more commonly describes these plants, since woody plants (i. more...

e., trees and shrubs) are always perennials. Perennials that flower and fruit only once and then die are termed monocarpic (semelparous). However, most perennials are polycarpic, flowering over many seasons in their lifetime.

In warmer and more clement climates, perennials grow continuously. In seasonal climates, their growth is limited to the growing season. For example, in temperate regions a perennial plant may grow and bloom during the warm part of the year, with the foliage dying back in the winter. These plants are deciduous perennials. Regrowth is from existing stem tissue. In many parts of the world, seasonality is expressed as wet and dry periods rather than warm and cold periods. In some species, perennials retain their foliage all year round; these are evergreen perennials.

Examples of evergreen perennials include Begonia and banana.

Examples of deciduous perennials include Goldenrod and mint.

Perennial plants dominate most natural ecosystems. For example, grasses and most forbs on the prairie are perennials. Perennial plants are usually better competitors than annual plants, especially under stable, resource-poor conditions. This is due to the development of larger root systems which can access water and soil nutrients deeper in the soil and to earlier emergence in the spring.

Perennials can be grouped by hardiness. For example, varieties that flourish in Missouri may not survive a Minnesota winter. In the United States, the Department of Agriculture publishes a hardiness map, using average minimum temperature ranges to form a zone numbering system. The higher the zone number, the less hardy the plant. For example, a zone 8 perennial, suited to a minimum temperature range of 10 to 20 degrees F, will not survive a normal zone 4 winter, which has a minimum temperature range of -30 to -20 degrees F.

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