Bamboo on boundary line...mine, or hers?!

Hi all - I'm having a new fence installed next month and have a clump of bamboo that, unfortunately, has spread into my neighbour's garden, underneath the fence line (I'm just 'sharing' my bamboo with her, just as she 'shares' her brambles with me !!). I really need to cut away that 'shared' part, so that it doesn't wreak havoc with the new fence. My question is...is the bamboo growing in her garden considered 'mine' (as it comes from my clump) or 'hers' (as it is growing in her garden)? She has already given me 'permission' to go into her garden to attempt to clear the brambles...
Any advice gratefully received!

 

Hi

Just ask if she want to have the bamboo or not and just explain about the new fence .. she may say yes take it out and if no you will try your best to leave some in ....

 

The bamboo is the gun, roses are the cannoli.
The godfather reference is not helpful to this thread, but sounded quite amusing in my head

 

Thanks for that - and yes, I am in communication with her, and wanted to know the 'legality' so that I was forewarned in light of any disagreement. Hopefully she will be ok with me trying to remove it from its present position, at least.