When creating particles that resemble leaves you basically have two options. The most common one is to take a photo-realistic texture with an alpha channel and use this on a simple uv-mapped rectangle. Another approach is to model the leave, with as little geometry as necessary, and use that as a particle. Here are NO texture with alpha, just an leaf object with 4 diffuse colors of green. 8 leaves puted in a group and added to hair particle, at the wall and a sphere. Blender Interenal Renderer. Use particle settings no 002 in a file.

YouTube link: https://youtu.be/Y_BeVznuZyo