The translucent node on the main node is a leftover from earlier versions of Poser and was an SSS fake rather than true SSS (uses ambient rather than true SSS). If you want translucent leaves and have a version of Poser 9 or newer, use SSS...I'd use the Custom Scatter node for leaves.

Try a blender node, plug that black and white map into it and make the white part of the texture SSS and the black part solid (or whatever it is you're after). The blender node can create kind of a mask for you and break apart the black and white into separate parts that you can manipulate individually.

Laurie