Thorny, sharp-leaved plant with yellow flowers?

May 13, 2013 3:08 PM

I (foolishly) let a plant with thorns and sharp leaves get rather large next to my house. Now I'm finding it tough to tear it all out because it's so well established. Can anybody help me identify the plant so I can try to figure out if I'm killing enough of it so that it won't come back? I live in Colorado. A picture of the plant is here and a close up of the yellow flowers/leaves is here.

The leaves are a shiny green with sharp, pointed edges. The stems are thick and woody and yellow inside, with thorns. They are a couple feet tall now. I can't get all the roots up - I'm digging down a bit before cutting it, though, and I just had the idea that I could spray the cut root with a bit of Roundup too. Should that kill everything?

posted by warble to Home & Garden (6 answers total)

Best answer: That looks like Oregon grape.
posted by ottereroticist at 3:14 PM on May 13, 2013 [1 favorite]

It's a Mahonia.
posted by lydhre at 3:19 PM on May 13, 2013

Both of those are Oregon grape but the spikier short version is, well, called short Oregon Grape while the other is called, predictably, tall Oregon grape.
posted by fiercekitten at 6:03 PM on May 13, 2013

Best answer: Yes, spray the cut root with Roundup. Use straight concentrate if you have that. I have successfully used this method in the past.
posted by eleslie at 6:28 AM on May 14, 2013

Best answer: Grapes put down taproots. They will grow back if you don't dig the root out and poison it completely.
posted by KRS at 7:17 AM on May 14, 2013

Response by poster: Wow, thank you everybody! This is all really useful information. I will go to town on the roots as much as I can and hope that does it.
posted by warble at 8:42 AM on May 14, 2013