I know the role of Vitellia in La Clemenza di Tito is written for a soprano.

However, would it be acceptable for a mezzo to sing Non piu di fiori as a recital piece?

-MZD

Believe it or not, I have a recording of Janet Baker singing the role! She's as mezzo as they come.
Besides, for a recital I say do it! If you can sing it and do it justice... that's the beauty of a recital!

on a recital with the Clarinet obligato and piano. If it suits your voice (tessitura,range) why the hell not?

This is one of my favorite arias for chicks. It sits reeeeeal low and then also goes up pretty high. But if you're a solid mezzo with low notes it should give you no problems. Lots of mezzos sing it, at least in recitals/CDs/excerpts etc. It's unlikely you'd be able to handle Vengo aspettate or Deh se piacer mi vuoi, but this should be no problem for a recital. Good luck!!

But sadly, no for auditions. I have been told this many times by coaches and such - I MUCH prefer this aria to any of the other Mozart options available to me (including Parto, etc), but any time I ask anyone who regularly hears auditions what they think about mezzi auditioning with it, the answer is a resounding NO WAY. Wah! But definitely use it for your recital! It is FIERCE!