This last photo is of a "mutant" coneflower. The petals are shaped differently (shorter) than usual, and they start out green-- and stay that way for a while.
At first, I thought this was just some harmless, interesting mutation, but after a bit of research, I wonder if it might be aster yellows, a disease that is fairly common in coneflowers (and a few other types of flowers, including marigolds, zinnias, and coreopsis-- not to mention edible plants and weeds). It can be spread from plant to plant by certain insects and is incurable, so it's best to remove and destroy (do not compost) affected plants as soon as possible.
It's a shame, but I guess I'll go ahead and throw this plant away today. (I hope I haven't hurt the surrounding coneflowers by leaving it as long as I have; it hadn't occurred to me that it could be aster yellows, since the flowers aren't completely deformed...)
Fortunately, purple coneflower is easy to grow from seed, so it won't be any problem getting new plants to fill in any empty spots.
