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* 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.

*also available in ShareCG, DAZ, and HiveWire3D flavours (the DeviantArt and CGBytes flavour have been discontinued).