Q: We are considering purchasing a home with large, mature trees in the front yard that have ferns growing on the branches in a couple of places. Is this a sign of weakness/illness in the tree?
A: The ferns are no problem at all. They are called resurrection fern because they turn brown in times of drought.
When it rains, they transform themselves overnight into a sea of tufted greenery on tree branches. Consider yourself lucky to own such a fascinating plant. Point the ferns out to friends who come to your housewarming!
see also Transplanting Resurrection Fern