...But is it really that useful?

Can any foodie GTers help me out here? I'm planning a dinner for Friday, and the recipe for the marinade I'm going to use calls for lemongrass, along with soy sauce, honey, ginger, and garlic. Now, I have everything else on that list, but I'm going to have to get lemongrass especially for this dish - can I replace it with lemon/lemon zest or forego it entirely and end up with a successful marinade, or is the lemongrass the key ingredient that keeps it from becoming a bowl of sadness and regret? I've only had foods with lemongrass in it a few times, and I can't really remember whether or not it added anything special, but maybe someone can help me out?