If you are talking about in the "sculpted" geometry, unfortunately not -- this is limited by the grass settings and random seed value.
If you are talking in Maxwell Studio then absolutely -- this is part of the reason for stacking modifiers. This way I can have several variations in materials (dry/dead grass, green grass, newshoots, etc.) and variations in the way the geometry is generated -- for instance: dead/dry grass is going to be much thinner and generally lower to the ground than green grass.
In this way some clumping variation can be added for mixed grass types (very common in more wild areas) -- the sky is the limit. Just remember that for each stacked modifier you want to reduce the density amount accordingly so as to not end up with too many blades.
Example: I have 1 modifier and conclude that a density of 4000 is sufficient -- if I add another modifier I should reduce both to a density of 2000 (or any balance that restores 4000 at the total number).
Best,
Jason.
