Plant editor question

[Bill Gilliss]

When making a grass groundcover, I can figure out what most of the settings are supposed to do. But what does "Underside" do? I do not see any effect in the Plant Editor raytrace window or in the rendering itself for fairly low settings, like from 0 to 5,

[Roy Hirshkowitz]

The fact that it's still an integer means I probably never got that working-- it was supposed to affect the underside of the leaf to differentiate it.  Not really sure what I had in mind.