I do know that you can grow roses from rooting the canes but I've never heard of it being done with just a leaf.

I'm not sure what the names of these parts are but its not just the leaf. It was cut off the stem so there is some stem going toward the leaf. I think that is what you mean by cane? I been looking into it and i think it is called the 'Petiole'?

I've never rooted a cutting (what I suspect you have is called a cutting, which is part of a stem that is cut off) before, but since no one has answered your question I'll give you a few links that might help:

http://scvrs.homestead.com/Cuttings1.html

http://forums.gardenweb.com/forums/load/rosespro/msg0403203512428.html

http://forums.gardenweb.com/forums/load/rosespro/msg0909424020840.html

Good luck!

Although I have heard of some plants being done by leaves, I can't imagine that getting a cane from your friend would have been too much harder.

Definitely give it a try because it's fun to experiment and learn things about gardening, but if it doesn't work well, then next time, try some canes.

Other than that, keep your soil moist but not too wet.