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(quack grass, or couch grass), a genus of plants of the family Gramineae. The plants are perennial grasses that often have a spreading rootstock. The inflorescence is a double-rowed spike. The spikelets, which are two- and many-flowered, are laterally compressed; they are situated singly on ridges of the axis and face the axis with their broad sides. The glumes are sharply pointed and sometimes awned.
There are approximately 150 known species of quack grass (including Roegneria—which is sometimes assigned to the genus Agropyron and sometimes to a separate genus). The USSR has 51 species of quack grass (not counting Roegneria). The plants grow almost everywhere: in fields, meadows, orchards, gardens, steppes, forests, and ravines.
The genus Agropyron is divided into two subgenera: Elytrigia (38 species in the USSR) and Agropyron (wheatgrass). Many species of the genus Agropyron are valuable forage plants; others are pernicious weeds. Some species (A. glaucum, A. elongatum) have been successfully crossbred with wheat.
The most widely encountered species is the common quack grass (A. repens), a long-rhizomed grass that grows under various ecological conditions. The plant prefers loose, nitrogen-rich soils. It is distributed on wastelands and river floodplains; it is also a component of meadow herbage and in mountain regions grows up to the subalpine zone. Quack grass is winter-hardy and drought resistant. A forage plant, it is eaten by agricultural animals as pasturage (before flowering) and hay (before flowering and in the flowering stage). One hundred kilograms of hay contains 51.7 feed units and 6.7 kg of digestible protein. Hay yield is up to 80 quintals per hectare.
The common quack grass, a weed that is difficult to eradicate, contaminates field, garden, and orchard crops. It is also found in large numbers along roads, fences, and ditches. On loose soils the rootstocks lodge to a depth of 20 cm or more, and on compacted soils, 10–15 cm. The rhizomes and young shoots easily withstand severe winters. Rhizomes cut into pieces while the soil is being worked are capable of growing and yielding new plants. The weed may be distributed with the seed material of other grasses from which its seeds are difficult to separate (awnless brome and wheatgrass). It is also distributed when transporting hay that was gathered when the quack grass seeds matured. Control measures include the implementation of a system of cultivation directed toward destroying the rhizomes and suppressing subsequent weed growth by plantings of agricultural crops. Herbicides may also be used.
Other species of the subgenus Elytrigia of particular value as forage plants in the USSR are A. intermedium and A. trichophorum. Of the genus Roegneria, A. tenerum-Roegneria trachycaulon is important as fodder. Introduced into cultivation in the USSR as a forage plant (imported from North America), it does not grow wild.
REFERENCESKormovye rasteniia senokosov i pastbishch SSSR, vol. 1. Edited by I. V. Larin. Moscow-Leningrad, 1950.
Kott, S. A. “Pyrei polzuchii.” In Biologiia sornykh rastenii. Moscow, 1960.
N. K. TATARINOVA