Jeff Patton posts a small tutorial on creating leaves using two sided materials in Mental Ray accounting for the leaf’s translucency and shadow attenuations. Check out the tutorial here.
A while back Peter Guthrie (a very talented artist) posted a VRay tutorial on making leaves using the VRay2sidedMtl. In this post I wanted to try and create a similar effect using mental ray in 3ds Max. Read on for further details.