Strange xfrog plants

[TerraCr8tor]

Hi Guys and Girls.

I've got some Xfrog plants that  have a strange  blackrectangle around some blades or flowers .
see image.

Can someone explane me how to prevent this ??
Also included the xfrog file

[yossam]

See the attached .tgd  Look at the opacity tab for the parts shaders for the plant. 

[TerraCr8tor]

Thanks a lot for your information  it works well