annual

annual

[an-yoo-uhl]
annual, plant that germinates from seed, blossoms, produces seed, and dies within one year. Annuals propagate themselves by seed only, unlike many biennials and perennials. They are thus especially suited to environments that have a short growing season. Cultivated annuals are usually considered to be of three general types: tender, half-hardy, and hardy. Tender and half-hardy annuals do not mature and blossom in one ordinary temperate growing season unless they are started early under glass and are set outdoors as young plants. Hardy annuals are usually sown where they are expected to bloom. Quite often they reseed themselves year after year. Blooming is prolonged by cutting the flowers before the seeds can form. Typical annual flowers are cosmos, larkspur, petunia, and zinnia; annual vegetables include corn, tomatoes, and wheat.

See H. G. W. Fogg, Dictionary of Annual Plants (new ed. 1972).

In a cross section of the stem of a woody plant, the amount of wood added during a single growth period. In temperate regions this period is usually one year, in which case the growth ring may be called an annual ring. In tropical regions growth rings may not be discernible or are not annual. Even in temperate regions growth rings are occasionally missing; and sometimes a second, or “false,” ring may be deposited during a single year (e.g., following defoliation by insects). Nevertheless, annual rings have been used in dating ancient wooden structures, especially those of American Indians in the dry U.S. Southwest. Changes in ring width are a source of information about ancient climates.

Learn more about growth ring with a free trial on Britannica.com.

Annual is typically used to describe something that happens once a year. Circannual describes events that take place over the course of one year and repeat year after year.

It may also refer to the following:

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