Bitter Greens?

"Greens have come a long way since Mom urged you to eat your
spinach. Nowadays, farmer's markets and even supermarkets are
loaded with seemingly exotic leafy crops, especially at the height
of the summer- making this a fitting moment to explore dark greens
beyond spinach-and-chard land. Not only do varieties like dandelion,
mustard, and escarole bring a peppery nuance to salads, pastas, and
more, but they are legendary as bountiful sources of disease-fighting
antioxidants."

-Whole Living Magazine July/August 2011