Ligularia mystery.

In our shady beds near the stream at work, we have several patches of Ligularia 'The Rocket'.

One of these patches seems to have been completely taken over by a different type of Ligularia, which is far more vigorous than 'The Rocket', out competing the original plants with ease.

Question is, what is it?

We also have some patches of the purple leaved Ligularia, dentata 'Desdemona' in some
nearby beds.

So what do we have here? Is this a reversion from 'the Rocket' to some parent variety or wild ancestor, or some kind of strange Rocket/dentata hybrid?

Any ideas?

 

It looks like Ligularia 'Zepter'....

 

Could be 'Zepter' Lol, but not sure the flower spikes look right. What's baffling me is those strange, bulbous flower spikes on our specimen, can't seem to find anything which looks quite like that.

 

It's the flower spikes that have got me stumped Trunky

 

Definitely looks like the flower of the Ligularia but that bulbous spike is a mystery!