Looking at the last comparison on the page, the grass isn't just becoming green, it's being "puffed" out from its original geometry, as if the grass geometry is

Looking at the last comparison on the page, the grass isn't just becoming green, it's being "puffed" out from its original geometry, as if the grass geometry is being vertex-shaded with small spiky-ball-like objects. (A bit like the look of "static grass" in model making.)