Carrion Vine is a useful skill that functions similar to the Paladin skill Redemption. Both have the effect of rendering dead corpses useless to others like Necromancers and enemy monsters, but there are differences. Redemption heals a set amount per corpse, while Carrion Vine heals a percentage. Both have their advantages and disadvantages, but the more life the Druid gets, the more he benefits from this skill.
In any case, this skill is much more useful than the prerequisite Poison Creeper, and one points can be a a worthwhile investment if + skill items can bring up the rest.