Quick experiment. Four leaves, two are one-sided flat zero thickness, two are solid volumes (basically just the flat ones extruded, with all normals facing out). bagginsbill's scatter node leaf shader without the reflect part, using a texture image and derived bump.

Worldball for IDL, and one infinite light with raytraced shadows. Poser 9 render as per the two posts above.

Lit from in front by the infinite:

And backlit:

Definite nice translucence effect on the backlit solid-volume leaves.

(Can't tell whether that's translucence on the flat leaves - done a couple more checks - it isn't, just the leaf colouration)

(Worth noting - I'm looking at the front of the one-sided leaves for the backlit image, i.e. I can see the leaves in preview mode. For the front lit view the flat leaves don't show in preview mode)

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The 3Dcheapskate (also available in DAZ and HiveWire3D flavours) occasionally posts sensible stuff. Usually by accident.
And it usually uses Poser 11, with units set to inches. Except when it's using Poser 6 or PP2014, or when its units are set to PNU.