"Michael Lyons" wrote
Austrilian Tree fern (Cyathea cooperi) for one. I fell in love with it
while
visiting Bok Tower Gardens in Lake Wales, Florida (zone 9b). Sunset
National
Garden book says it grows in zones 15 to 27 of their zone system. It says
that they can get as high as 20 feet with a 12 spread. The fronds are at
the
top of a trunk, and walking under them is no problem when they get big
enough. The ones I saw may have been 12 tall and provided shade for other
plants.

Ah, sounds wonderful but not for central Indiana, I fear.

Giselle (would LOVE 7' ferns )