I wondered about Asclepias. The same day I took the pic I planted A. tuberosa in a sunnier area. These are growing in a fairly shady place but the butterflies were on it. I thought the foliage on this one was different from the one I planted. Possibly another species?
I have a friend who recently offered me seeds of Asclepias currasivica. Judging from pictures it seems a possibility, I'll try to get by to look at his plants soon. These are growing in the mountains of western NC and in a fairly shady place, which I would not have expected for that plant. Of course my expectations are often proved incorrect. Thanks for the suggestion.
Hcmcdole, that's why I was/still am skeptical. Of course it does spread quite a bit by seed and I was surprised to see on the USDA site that one of the states in which it has naturalized is TN. I thought I noticed the foliage being different on the plant I found from the one I planted, but it may be that some of the foliage on the found plant had been eaten by caterpillars. I will mark the plants before Fall and see if they return in the Spring as a perennial. That will also help me keep track of them through the rest of next year. I appreciate your thoughts.
I looked up Planthera cristata and I believe/hope you are right. The two plants are just about a foot apart, still I feel a bit silly to have thought they were the same. I'm excited to go back up to check on them and mark the area to look for them again next year. Thank you all so much for the help.