We all know that greens reign when it comes to nutrition. But is there a hierarcy among them? Nutritionist Cynthia Sass reveals why these popular little greens that are now being found in trendy restaurants are an excellent health food and better for you than their full-grown counterparts. Next time you're in the grocery store, pick up a pack of them to try in your next meal.

RELATED: Need some healthy meal ideas? Try one of these 40 easy recipes under 400 calories.