I don't have the southwest plants package, so I can't check that on my system. As far as the textures, I find that with a lot of the leaves, the edges of the textures aren't smoothed out at all, and since they're tiffs, with embedded alpha info, the edges of the alphas are rough as well. I usually do some smoothing and smudging at the edges of the color maps, and then even out the edges of the alpha information, plus I change the background of the color maps to a color closer to the leaf color. That way I don't end up with artifacts around the leaf edges. For an example of what I think is a sloppy map, check the papaya leaf, I think that's one of the worst.

Sgiathalaich