I think this is another example of fasciation (remember the fasciated lily last year - was it Marcia's?). The latin 'fascia' means to fuse, which seems to be the case here.

I've never seen this on my Doronicum, but it often happens with my Painted Daisies. Apparently fasciation happen one year and not the next.

I wonder what causes it. It affected several stems. Thanks Pudge.

Yes, those were my lilies. Someone just told me that it looks like theirs will do it this year. And i've seen a couple of fasciated dandelions this spring - just what we need, eh? LOL