Okay, I grow this plant, Polygonum cuspidatum variegatum;I'm not proud of myself but I love the orange colored shoots that force their way out of the ground...well, now. If you know a bit about invasive plants, you may know that the parent species of this plant is a dangerous invasive colonizer native to Japan that has been introduced throughout the world. Officially designated a noxious weed in the State of Washington, it is a much more serious problem in Great Britain.
There are a number of variegated forms and the unaggressive nature of this clone is generally acknowledged but never explained. The species is dioecious, meaning that the flowers are either male or female and the individual plants are either male or female. Apparently all the Japanese knotweed in Great Britain is a single female clone!
I grew this one for 10 years in a barrel and it never moved beyond a tight clump in the middle of the barrel. I always watched it suspiciously worrying that the vigorous rhizomes would force their way out of the container and into the soil. I was prepared to kill it at any time. Well it never escaped and I never felt compelled to kill it. At some point, the barrel rotted and I planted the Knotweed in the ground. I watched it even more carefully. Five years and no problem but I know that doesn't mean I can relax and frankly after making this public confession I am going to enjoy the shoots one more spring and next month it will die.
Sometimes we grow plants for funny reasons; like the shoot color of new growth. I guess sometimes we have to kill them for other reasons. Removing a plant from the garden always comes with an upside. Room for new plants!