Changing textures in one area and ignoring another

[laager]

I'm making a texture mod that changes some plant textures. Some of the plants are growing all over Skyrim, and I want the mod to affect all regions of Skyrim where that plant is growing EXCEPT the tundra. Is that even possible? I'd guess not at least before CK comes out, but do you think it can be done easily with CK? I haven't used the previous kits much and haven't scripted anything in almost ten years, so I'm not very advanced in that area. However, I don't really like the fact the mod is affecting the flora of the tundra and I'd like to fix that, although it's not really a huge problem.