I'm trying to create a plane and attach Fur (grass) to it. The problem is in the view port, it looks good but when rendered, the grass makes a rectable. The geometry was made using the Create polygon tool so it was never a rectangle.

I have tried making the pattern using extrude. I've tried using booleans. I've tried making a square and adjusting verts. But no matter what I've done so far, I can't figure out how to make it put grass only on the geometry. It always wants to make the grass 4 straight sides no matter what. Anybody have any ideas?

The top picture is my viewport, grass only shows on geometry it was assigned to. Bottom picture is a Mental Ray render.

Edit: Oh yeah, I've tried creating UV's with the projection (Y) method and also with the auto method.