We've talked about the power of leafy green vegetables before, so it's time to dig in and really understand how good these are, whether any stand out from the crowd, and if there are any drawbacks to eating bushels of romaine, arugula, spinach, or kale.

• The Etymology of the Word Arugula - Bon Appetit
• Romaine's Long Leafy History - Washington Post
• Iron and Popeye