Mystery plant in flowerbed

Hello, I have a mystery plant in my flowerbed.

Each plant is about 3'6" to 4', growing on long, single, hollow stalks. Leaves are wide and pointed, the size of my hand or bigger. These are VERY determined plants. We keep digging them up because I don't like them and want to replant other plants, but they keep coming back. They do not flower, that I have seen. I'm hoping that if I find out what they are, I can be rid of them more easily! They only grow in my flower bed, and only in one area of that, so I don't think they are a weed.

Thanks!

Natalie

 

could you post a picture, im sure it will be identified :)

 

I'll try and take one this year. In the past, I have just been trying to kill it more then identify it. Things are starting to warm up and green things are growing, so it might be a while until I can take a good picture. Any guesses in the meantime would be appreciated! I'm hoping the hollow stalk is a very unique characteristic.

 

Could it be knotweed?

Is it this plant?
http://www.mda.state.mn.us/invasives/knotweed/default.htm

 

Yes! Thank you very much. I did some google searching on it and it's very hard to kill, unfortunately. Wish me luck!

 

Uh Oh! We had a problem with Knotweed when I was at college. It regenerates even from the tiniest amount of root left in the ground and can be a total nightmare. The best thing we found was to cut the stems about 6 inches from the ground, burning all the rubbish and then injecting a strong dilution of Roundup into each of the hollow stems. Painstaking but effective! We tried spraying first but to no avail and weeding by hand seemed to make things worse.
Good luck!

 

Thanks for the suggestion! I'll give that a try first!

 

The non-chemical approach is discussed in this thread:

http://www.botanicalgarden.ubc.ca/forums/showthread.php?t=384

 

Thank you, I had seen a similar approach on this site:

http://landscaping.about.com/cs/weedsdiseases/a/knotweed.htm

I plan to use a combined approach of chemical and non-chemical means. I can't really mow the area, as it is in a flowerbed, and I think it's too thick for a weed wacker, but from what I have read, injecting with herbicide and covering with a tarp, combined with constant pruning *should* do the trick... after a year or two.

As that site says, I'll have a new hobby... killing this plant.

 

Remember that mowing and weed whacking will spread the plant. It regrows whole new plants from all those pieces.