Knotweed


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Knotweed

 

the name of more than 30, mainly Middle Asian, species of perennial plants of the genus Polygonum. There are about 15 species of knotweed in the USSR. The flowers have a corollaceous perianth, usually with eight stamens and a three-parted style; they are gathered into a loose panicle.

The best-known species is P. coriarium, which is found in Middle Asia in mountain zones at elevations of 1,700 to 2,800 m above sea level. The plant, which often forms an extensive dense cover, is usually 1 to 2.5 m tall and has a strongly developed root system. It is a valuable tanning plant; its roots have a tannin content of 15–25 percent. Several other closely related species, including P. songoricum and P. hissaricum, also yield tanning agents. The species P. alpinum is found in Middle Asia, the European USSR, the Caucasus, Siberia, and the Far East; it grows on plains, in mountain meadows, in steppes, along the edges of forests, and on rocky slopes. Its roots contain tannins. All knot-weeds yield significant amounts of nectar.

REFERENCES

Taran dubil’nyi (Polygonum coriarium Grig). Tashkent, 1959.
Voprosy izucheniia i ispol’zovaniia dubil’nykh rastenii v SSSR. Moscow-Leningrad, 1963.

M. E. KIRPICHNIKOV

References in periodicals archive ?
After completing a course, he sat a specialist Japanese Knotweed qualification and launched his own business in Dolgellau, having returned to his home town.
Mr Waistell said the rail owner has sprayed the knotweed behind his house in the past, but he claimed the work was done inadequately and inconsistently, which is why the plant continues to grow extensively up to the rear of his house and others.
Richard Podmore, joint managing director of Japanese Knotweed Control, explained: "There is a known case of knotweed infestation in at least every 10km square of the British Isles, but some areas are much more at risk than others.
However, it was agreed last month that Japanese knotweed in council tenants' gardens will now be dealt with by the council to ensure a consistent approach in tackling the issue across the city.
We would however only consider this action where residents are taking no action, and as a result this is causing knotweed to significantly spread on to neighbouring land.
The knotweed in both areas was identified by Streetscene officers as they undertook routine works, and any other areas that come to light during the growing season will also be treated," the spokesman continued.
Japanese Knotweed is regulated by several acts of legislation which puts a duty of care on the landowner to be proactive in the control and eradication of it.
Experts have hailed the trials as ground-breaking progress which will eventually help bring the knotweed plague under control.
Japanese knotweed, inset, can even 'play dead' - rhizomes can stay dormant underground for as long as 20 years before producing plants.
Japanese knotweed is listed as one of the 100 most invasive plant species by the World Conservation Union, and Oriental bittersweet has been infiltrating the North American landscape since 1879.
Meikle said: "This non-native species is a hot topic at the moment due to a number of lenders refusing mortgages on properties which are found to have knotweed.
We now specialise in a number of areas - domestic and commercial grounds maintenance, tree work and dealing with invasive species like Himalayan Balsom and Japanese Knotweed.