This grows a wall of trees out of the ground with DR 9, HP 3.

Innate Attack (Crushing) 3d [77] 
    Area Effect (2 yard radius) [+50%] 
    Persistent [+40%] 
    Wall (Rigid, Shapeable) [+60%] 
    Extended Duration (Permanent) [+300%] 
    Environmental (Requires dirt floor/ground) [-20%] 
    Magical [-10%] 
    Spell Components [-10%] 
        Must say "wood" in Latin 
Level 2 [84] 
    Increase Area Effect by 1 step [+50%] 
Levels 3+ [+7.5/level] 
    Increase Area Effect by 1 step [+50%]