No, it is not. It does not have the Zone Attack symbol. It is on par with level 1 attack spells like Flameblast and Arc Lightning. Burst of Thorns has a greater range than most level 1 attack spells and has piercing +1, but it requires the expenditure of one of your vine markers. Also, a lot of the attack spells are unavoidable, while Burst of Thorns isn't.