Perennials


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Perennials

 

(also perennial plants), herbs and subshrubs that persist through more than two winters. Some perennials live several years, and others 20 to 30 years. Some species have a life-span of 100 years (for example, tau-saghyz). Upon reaching a certain age, perennials may flower and bear fruit every year (polycarpic plants); this contrasts with annuals and biennials (monocarpic plants), which flower and bear fruit only one time. Some perennials retain their leaves year round (evergreens). In unfavorable periods (winter, drought), the leaves and other aboveground organs of most perennials die, and only the underground organs remain alive (rhizomes, tubers, bulbs, and roots). In some perennials the aboveground shoots are partially preserved as well (rosettes, creeping shoots, and the lower parts of erect stems).

Sometimes the division of plants into annuals, biennials, and perennials is conditional. For example, the tropical perennial castor oil plant (Ricinus communis) grows as an annual in moderate climates, and annual bluegrass (Poa annua), which generally grows on plains, develops as a perennial in the mountains. Trees and shrubs are sometimes referred to as perennials.

REFERENCES

Serebriakov, I. G. Morfologiia vegetativnykh organov vysshikh rastenii. Moscow, 1952.
Botanika, 7th ed., vol. 1. Moscow, 1966.

L. V. KUDRIASHOV

References in periodicals archive ?
Youll find that giving your trees, shrubs and perennials some good hydrating during the fall will support their growth as spring arrives.
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The HGTV HOME Plant Collection has signed a new partnership deal with The Perennial Farm of Glen Arm, Maryland for the next year.
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Perennials are often offered on sale in the fall as a way of reducing inventory.
An analysis was constructed to determine whether differences existed between annuals and perennials for quantities of OC down the profile at each site.
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The herbaceous border has long been a feature of grand gardens where a range of perennial plants - tall ones at the back coming down to low species at the lawn's edge - provide a tableau of colour from spring right through to late autumn.
Burning in winter, when soils were wet or frozen, helped limit damage to existing perennials at the site and gave them a head start in their growth the following spring, when they needed an edge against invasive annuals.