A while back I came across a paper that had a list of crosses that were known to work without embryo rescue and posted it here:
http://garden.org/thread/view_...
So certainly some
intersectional hybrids are possible without needing special techniques (the standout in that list is
L. speciosum X
L. nepalense). In the majority of cases, though, my guess would be probably not.
Edited to correct interdivisional vs intersectional (thanks Leftwood).
