annual (redirected from annual mercury)

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.

Bibliography

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

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annual

Any plant that completes its life cycle in a single growing season. The dormant seed is the only part of an annual that survives from one growing season to the next. Annuals include many weeds, wildflowers, garden flowers, and vegetables. See also biennial, perennial.