artifacts with node generated leaves

Question

To create multiple leaves on the ground I followed a tutorial and used nodes to create. On some leaves I have this black color and lines. Don't know what is causing this.

I tried turning off shadows but that didn't help. Below is render and Blender file

https://app.box.com/s/mflioj2w9kmkhw07n4q2p51d61a94eeu

https://app.box.com/s/2ww4ghred1deplm0urtem34ergp2cdr0