Mystery rhizome/tuber

Can anyone identify this large corm.tuber/rhizome? Dug up yesterday to enable wall to be repaired. Shoots just starting to break. No idea what it could be. Not rhubarb, not nerines.

 

Wild guess, canna?

 

Might be, though the roots look thin, black and wiry rather than thicker and light coloured….

 

Geranium Mac.?

 

Not geranium mac. Rhizome bits much thicker, some of the bulb like bits are the size of large daffodil bulbs.

 

Darmera peltata?

 

It wasn’t growing in a particularly boggy area of the garden, it was at the base of a shady wall. There is a bog garden, so as the previous garden owner was quite a plantswoman, I might have expected it in that area. I think I’ll just pot it up and wait and see. I’m just impatient!

 

Bergenia? I dug one up by mistake the other day and it looked quite similar!

 

I reckon bergenia

edit

I also reckon I've been beaten to it!

 

If it is Darmera it wont like being in a pot. I haven't checked ours but both on the fringes of our pond. Too wet today to do anything in the garden but hopefully will have a look tomorrow.

 

My Darmera tubers don't really look like that, they look more like large Bearded Iris tubers.