There are a number of Miscanthus sinensis that get into the 9' range. Cabaret, Cosmopolitan, Autumn Light, Bronceturm, are all really tall. I've seen some Strictus get surprisingly tall as well.

in zone 5/6 our miscanthus max out at about 6/7 feet.gigantus goes to about 12 to 14

I have Miscanthus xgiganteus (Giant Miscanthus) that easily reaches 12-14 feet. The first couple of seasons it toped out at around 9 feet. It's so thick that deer don't go through it. Everyone who sees it wants to know what kind of grass it is. ItÂs impressive!

I have the hybrid 'Gigantus', I don't think it got to 10' last year. Now my Arundo donax got 12-13' last year. The Reed Grass has overtaken the 'Gigantus' this year maybe 10' to 8' so far. 3rd summer for both.

I also have 'Strictus'. It's 6' now. Such a nice strong plant. They need to have an all dark green version of 'Strictus', would make a great screen.

I also have 'Grosse Fontaine', maybe the blades get as tall as 'Strictus', but it droops much more. Its getting wide in it's 4th summer. I want a miscanthus even taller and stronger, with redder inflourences and better fall color.

Yes, I just get bored and want to change things.