Take that kale! Watercress is number one powerhouse vegetable - ABC News (Australian Broadcasting Corporation)
Avert your eyes, Jason Soon - an article all about the good things in green leafy vegetables.
I see that kale is said not to be that great a "superfood" anyway. I'm relieved to hear it - there are few vegetables I actually ask my wife not to buy, but kale is one of them. Its tough, rough leaves have never impressed me in the slightest - in fact, I positively dislike it - and I always suspected its popularity was a passing fad.
This report talks up watercress, which is one of my favourite bases for a salad. It can be bought cheaply from some street markets around Brisbane, at some times of the year, but seems to rarely appear in mainstream fruit and vegetable shops. There should be more of it.