I see your concern, that looks very unusual. I am afraid I have no idea. Hopefully somone may have an idea.

It doesn't look harmful to me just a disfigurement or something.

Hi Alexb, All the same many thanks, as you say it just might be a disfigurement ! keep up the gardening !.

I had something similar on a Smoke bush - we cut it out and it didn't grow back.

That my good friends is a classic case of fasciation. It is caused by some form of damage to the stem causing 2 or more buds to grow together and become fused. The word comes from the Italian meaning a bundle of twigs (It is also the root of Fascism from the Italian Fascist parties emblem of a bundle of twigs, but never mind). It is fairly common among many plants, but sadly anything propagated from it reverts to normal growth as it is physical rather than genetic. Prune it out and it will not recur.

Isn't it great that you can get such a knowledgeable answer here on the same day?! Impressive.

We's good we is!

History lesson as well, I agree Owdboggy you is good.......

better than a book!

I think it's called Fascination??

Would there be any harm in leaving it?
I'd quite like that if it was mine...

It will not do any harm to the plant to leave it where it is.

I have often had this in primula denticulata too. Its a wonderful abberation.

Thanks EVERYONE for you comments ( am new here!) very interesting owdboggy ... i like a bit of history ! i have been gardening a 'very long' time ! but have never come across this , always a first time for everything ... thanks again ,will probably prune it out at some point .

I have a Veronicastrum in my herbaceous border that does the same thing. It makes very wide flowers like mauve tongues on several stems. Does it every year. It has made a very large clump and seems very healthy and vigorous. Thanks for the posh name for it Owdboggy. It would make a good decoration for a flower arranger......not me.....I just stick em in vase.

i'd prune it i agree with what owdboggy says

Greenfingers, OwdB is correct the term is fasciation - fascination is an interest you have in something, for example "The fascination of growing alpine plants from seed is that you get varieties the garden centres don't sell'.