perennial(redirected from perennial ryegrass)
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perennial,any plant that under natural conditions lives for several to many growing seasons, as contrasted to an annualannual,
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.
..... Click the link for more information. or a biennialbiennial,
plant requiring two years to complete its life cycle, as distinguished from an annual or a perennial. In the first year a biennial usually produces a rosette of leaves (e.g., the cabbage) and a fleshy root, which acts as a food reserve over the winter.
..... Click the link for more information. . Botanically, the term perennial applies to both woody and herbaceous plants (see stemstem,
supporting structure of a plant, serving also to conduct and to store food materials. The stems of herbaceous and of woody plants differ: those of herbaceous plants are usually green and pliant and are covered by a thin epidermis instead of by the bark of woody plants.
..... Click the link for more information. ) and thus includes numerous members of the kingdom. In horticulture, however, the term is usually restricted to hardy herbaceous perennials, particularly border plants such as alyssum, chrysanthemum, iris, peony, phlox, pink, and sedum, all of which characteristically die down to the ground each year and survive the winter on food stored in specialized underground stems (corms, rhizomes, and tubers in horticulture; bulbous plants are not considered perennials). Perennials form seeds each year after reaching maturity, but since plants grown from seeds do not normally bloom until the second season (unless forced), most garden perennials are propagated by dividing the rootstocks (see propagation of plantspropagation of plants
is effected in nature chiefly sexually by the seed and the spore, less often by rhizomes and other methods (see reproduction). Vegetative means include cutting, layering, grafting, tissue culture, and division of the roots (see perennial) and of the tubers
..... Click the link for more information. ). In fact, division every few years—as well as judicious pruning—is usually necessary to prevent the plant's becoming straggly and weak. Perennials, including the woody perennials, may have a rest period of some duration during their life cycle. In the plant different parts rest at different times and resume growth independently, e.g., the buds of deciduous plants, which form in late summer and remain dormant until spring. Even in tropical areas where plants appear to retain their leaves the year round, some plants lose all their leaves for a brief period and others grow new and drop old leaves on a continuing basis, as do most conifers.
See R. W. Cumming and R. E. Lee, Contemporary Perennials (1960); J. U. Crockett, Perennials (1972); A. M. Armitage, Herbaceous Perennial Plants (1989); R. R. Clausen and N. H. Ekstrom, Perennials for American Gardens (1989); P. J. Harper, Designing with Perennials (991).