Leaf Unrounder makes the textures of leaves added by Biomes O' Plenty square-shaped when BetterFoliage's bushy leaves option is active.
Leaves without the resourcepack:
Leaves with the resourcepack:
Made for use on 1.7.10 with Biomes O' Plenty and BetterFoliage.
(Side note: I'm not sure if this is a bug, or an intended feature. There is an old issue about it on BoP's github, but it was closed without comment. I personally find it annoyingly inconsistant with other leaf types, hence this resourcepack.)