Acroptilon(redirected from Russian knapweed)
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(in Russian, Gorchak). (1) A genus of perennial herbaceous plants of the Compositae family. The stem is heavily branched. The leaves are mostly lanceolate. The blossoms are pink and tubular and are gathered into small calathidia that form a branchy inflorescence. The genus includes two Eurasian species. The best known is A, repens, which is found in the south of European USSR, in the Caucasus, in the south of Western Siberia, and from Asia Minor to Mongolia. It grows on steppes and slopes and also on fallows, along roads, and near dwellings. It is a perennial, soboliferous, quarantine weed. The stem is 30–60 cm high; the leaves are sessile lanceolate; the blossoms are small and are gathered into single calathidia at the tips of the stems; the fruit is an achene with a slightly drooping pappus. The root system is vigorous and consists of a main taproot that extends to a depth of 6 m or more, lateral roots, and vertical rhizomes. Acroptilon reproduces mainly by root suckers. It is drought-resistant and salt-tolerant. It is toxic to sheep, horses, and camels. It contaminates all young crops, especially cotton. Late-planted crops suffer especially. Control measures include quarantine, uprooting the subterranean portions of the plant with deep plowing and repeated cultivation, and the use of herbicides. Another Acroptilon, A. australes, is common in Middle Asia. Closely related to Acroptilon is Phalacrachena inuloides, which contaminates flooded lands in the Southern Ukraine, the Northern Caucasus, and the Volga regions in the springtime.
(2) Sometimes species of the genus Picris, also of the Compositae family, are called Acroptilon.
REFERENCEKott, S. A. Karantinnye sornye rasteniia i bor’ba s nimi, 2nd ed. Moscow, 1953.
T. V. EGOROVA