I don't know if this will work with VFT's, but I have propagated many 
tuberous begonias from leaf cuttings by laying the blade of the leaf flat 
on its back and slitting the main veins in the leaf with a razor blade.  I 
keep it under mist-- just moist enough to keep it turgid, but not so much 
that it rots.  Within four weeks there are plantlets forming at the cut 
sites.  I believe that auxin concentrates at the cut sites, inducing root 
and shoot formation.  Perhaps Venus Fly Traps act in the same manner?
Harry Haecker
(haeckerh@nwrc.gov)