Liveoak (Druid 6):
Liveoak must be cast on a healthy, Huge oak. A triggering phrase of up to one word per caster level is placed on the targeted oak. The liveoak spell triggers the tree into animating as a treant.
Changestaff (Druid 7):
You change a specially prepared quarterstaff into a Huge treantlike creature, about 24 feet tall. When you plant the end of the staff in the ground and speak a special command to conclude the casting of the spell, your staff turns into a creature that looks and fights just like a treant.