How to keep the vertex normals after deleting an edge/face? When replacing sparse quads with a custom mesh, I create a "base vertex" on each quad, in order to cause a Particle Instance modifier to spawn the custom mesh at the right place (like for spawning leaves on a tree created by the Sapling addon).

However, when I delete the rest of the quad, just keeping the wanted vertex, its normal is modified, making the Particle Instance modifier instantiate the meshes with an incorrect rotation.

How can I keep the normal as it is (aligned to the quad's face) while removing the useless vertices?

here is an example blend file : http://www.pasteall.org/blend/23530

Goals:


new leaves must have the same orientation as the sapling one.
they must look natural : they must have their base touching the branches.
their must be exactly the same number of leaves in the particle instance modifier as in the sapling version.
A single vertex can't have a normal vector. A normal is the vector which is perpendicular to two other vectors (edges) the normal is calculated using the cross product. 

A vertex normal is the average of all surfaces normals which contain a certain vertex, this does not mean that a vertex can have a normal. 

Perhaps you could move the original quads to another (invisible) layer.