Aster yellows can cause a wide variety of symptoms. This echinacea certainly fits the description. There is no cure, and I would dig out the entire plant just to be on the safe side. The fewer opportunities for this disease to spread (which is done by leafhoppers), the better.

rhizo

you would really take such drastic action based on one single flower??????

is there any reason to think that it is just some weird genetic anomaly ...

ken

I have lots of echinacea in my gardens, as well as other plants that could be affected by this disease. I wouldn't hesitate for one second to remove one if I suspected Aster Yellows.

Echinacea is, however, a plant that does commonly mutate. If the rest of the plant were normal (which it isn't), I'd suggest that the two heads were a sport.

It's an easy plant to replace and that's what I would do.

I think it's cool... I love it when my gerber daisies do that :)

I had a yellow gerbera daisy that did that this year. I thought it was really cool too, but the whole plant dies shortly after I put it in the ground.

I have some mexican hat that did that. Uh...just thought I'd share...