I was in contact with a long time native plant afficianato the other day and was told she has found the Jingle Bell/Threadroot/Harris' Orchid (Dendrophylax porrecta) on Buttonbush (Cephalanthus occidentalis) in here in Pasco County Fl. Any of you out there looking for this species may want to check out those bushes as well in your areas.
IIRC, Paul Martin Brown mentions this as an occasional host species in his book. He also mentions laurel oak and even the woody, dried leftover stems of some types of aster. I have yet to see it on anything besides pop ash, pond apple, eastern redcedar, and baldcypress.