Ortu,
I broke this up into 16 different memblocks based off a square grid of the map(only because this is what the game I am working on will do). So, in theory, at worst I will have a few showing, and at best only 1. I think the lowest vert count I saw was 216K.
1) I custom created the meshes in blender to reduce alpha-overdraw. In addition to the performance boost, despite the increase in verts, it also makes the plants look better, since mipmaps won't blend the alpha, as much. A lot of my foliage is only single blades/stems.
2) I have a total of 10 different plants, with 1 4k texture.
3) I then merged the meshes into a memblock and added the indices for a performance boost and vertex color data, so the plants bottom will not sway. The very bottom is total blue, and it fades off as you go up the plant. If there is no gradual fade the bend will look silly.
4) I do not show backfaces. As I created the mesh I made sure the normals would point up and towards the camera. In my project, the player can't turn the camera, so that is a nice bonus to performance, I think.