Great set of urban planted trees. A good balance between poly count and detail, with a naturalistic randomness to the branches and leaves. The circular/radial grates are probably going to get used the most and they are what you'd be more likely to encounter (at least in US cities) but it can hurt to have options. I ended up using all three tree variation for a project but stuck to the circular grate for them all. It's easy to give each of the three trees a little rotation so that they don't appear to be duplicated in your scenes. Good job on the VRAY shaders; I converted them to Mental Ray, which was a fairly simple process. The bump and specular maps could have been a little higher res, but the diffuse is what counts the most, and that's just fine even for closeups.