Spreading Mahonia?

I have a beautiful (and what I beleive is) a Mahonia Japonica in my front garden. And another with the purplish, shiny, leatherish leaved variety in the back nicely set against a small apple tree.

However, there are loads of the leather leaved type popping up all over the place. Its like a weed almost - do they spread by rhyzomes? And is there any way I can stop it? I have simply cut some of the 'strays' I have found whilst cutting back what are quite overgrown borders, but I don't think its the way forward. For information the bark inside is yellow.

Any help would be great. Whilst I think its a lovely plant on its own and the Mahonia Japonica is lovely and just flowering at the moment, I don't want it the other type popping up everywhere!

 

Can you post a picture hellsbells?

It would help a lot in describing what the problem plant is, I dont doubt its a mahonia, but there are a few different ones around and I think aquifolium could be the spreader.

 

its probably mahonia aquifloium (there may be other suckering types but thats the most common) You can cut of the suckers, another method is to dig a trench all round it, back fill with compost and keep cutting along the trnech to keep it restrained. My advice though, if you havnt got the space for a suckering shrub get rid, it will be a constant battle. Try a piece in a big container I think it might do well can cope with a bit of neglect should look really glossy and flower well with benefit of good potting compost?