Why are the objects in my hair particle system not sitting on top of the ground? I made a hair particle system and set the Dupli Group to a group of 3 objects. Each of the 3 objects has:


it's origin set to be touching the XY plane (on layer 2)
it's Scale applied to 1 and it's Rotation applied to 0




I am trying to get each of the objects to sit directly on top of the ground, but instead, they are centered in the plane, half above the plane and half below the plane:  



What am I doing wrong? Here is my blend file.
This is because hair particles use the global +X axis as "up" for orienting the particle.

If you rotate your objects 90&deg; on the Y axis so that the direction you want to be facing up is instead facing global +X, you get the following result:



It isn't necessary to apply the rotation, since you have Rotation enabled in Particle Settings > Render.

Note that if you don't have Rotation enabled, for some reason the "up" direction becomes global +Y, and you will need to apply rotation for changes to take effect.