Hi !

I grow a kind of black viola (they are several ones in fact, more or less big, more or less black): there are plenty of pics on google, take a look at the link :-)
About fragrance: only violets and not all of them (a few in fact) have a sweet perfume, I've never been able to find a fragance to a pansy except the one my mum's growing, and believe me it smells like a dead dog :-/

All the best :-)
Thierry

Here is a link that might be useful: Black viola