Detail texture and mesh for grass and bushes not rendering correctly on device

I'm trying to paint detail textures and meshes on my unity terrain, and they appear fine in the editor.

However, when I deploy to iPad, they either don't appear at all (in the case of textures), or they appear with black instead of transparency (in the case of meshes), and the textures look very low res.

I've tried both 'grass' and 'vertex lit' options. When I select 'vertex lit', the meshes look incorrect in the editor as well, as they do when I deploy to iPad. I think this is because they are formed of just 12 triangles, with 24 vertices, so aren't built for vertex lighting.

I'm using a standard shader. I've tried playing with different shaders but the results are the same. If I select any mobile shader, the meshes look incorrect in the editor, as they do when deployed.

Textures actually appear if I un-tick billboards, however they then have black where there should be transparency, and again, look very bad.

I've been trying to upload screenshots, but I keep getting a parsing error. Have tried both Chrome and Safari and a range of image extensions. And can't seem to add image links either(??). So descriptions will hopefully suffice. Any idea what I'm doing wrong? Many thanks.