Transparent textured planes produce black artifacts Having problems with hair transparency using cycles. I ported over a model from daz studio (have done this a few times before with no issues). 

Using a simple mix shader, transparent top, diffuse bottom, black/white texture in the fac.

Heres the blend http://www.pasteall.org/blend/39347 with images packed.
Looks like you need to increase the maximum number of Transparent Bounces in Render settings > Light Paths: