Unable to render an Alpha Transparant texture I am creating rocks with a group-hair particle system of leaves on top of the rocks. The leaves was just an alpha image being textured into a plane. It was working fine. 

However, when I render the alpha image, there are shadows of the plane. I wanted it just to have shadows on the leaf and not the alpha-part of the image. What is the cause? 
Here is the blend file.

P.s. I already checked transparency on the material of the plane and make sure to have zero alpha and spectacular. Also, when I render the leaves alone (not the particle system), it appears fine. Like on the pictures below.


There are shadows when in particle system.



Here is the Textures for the leaf (I can't get 3mb to upload here. Btw, the source was from a tutorial by Andrew Price):
http://www.pasteall.org/pic/75151
You're using buffer shadows, which according to the documentation cannot render transparent shadows.


  Raytraced shadows are generally more accurate, with extra capabilities such as transparent shadows, although they are quite slower to render.