Japanese Knotweed

aka Fallopia japonica, Reynoutria japonica and Polygonum cuspidatum

Most people visiting this site will probably be doing so with murderous intent - but as I never tire of telling people, I am much more interested in the sex life of Japanese Knotweed, than I am in killing it!   A lifetime's study of Japanese Knotweed has revealed a fascinating story, a giant female clone with tendrils stretching from Japan to Europe then onwards to North America.  Without a mate it has sex with any related species around. A riches to rags story - a plant once an expensive and cosseted prize-winner a plaything of the wealthy, reduced in the space of couple of decades to a life in the gutter, the road and canal side.  A plant that has spawned a mini-industry dedicated to its eradication and so loathed that it in Britain it is one of only two land plants proscribed by the 1981 Wildlife and Countryside Act.  But a plant that thrives on the edges of active volcanoes is not without its resources!  In the West large stands of it are extremely difficult to eradicate due to their massive network of underground woody rhizomes.  It has hybridised with the related Giant Knotweed to create an even more formidable enemy Fallopia x bohemicaResearch into the spread and reproductive biology of Japanese Knotweed has been undertaken at Leicester for more than 30 years started by the ground-breaking work of Conolly 1977.

Every Autumn throughout the Western World a thousand million feathery Japanese Knotweed stigmas flutter hopefully in the breeze, waiting for that special pollen grain that may hold the genes that will restore male fertility to the female clone and perhaps produce the 'groom of knotweed'!

If you have no curiosity and wish only to kill Japanese Knotweed.

Main Page

Research at Leicester Control  Biological Control  History 
F japonica Life cycle F x bohemica F sachalinensis F x conollyana
Identification Reproductive biology Hybridisation Japanese habitat Links

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