MSN takes a stab at the FDA in their “10 Best Foods” article:

Purslane

Although the FDA classifies purslane as a broad-leaved weed, it’s a popular vegetable and herb in many other countries, including China, Mexico, and Greece.

Why it’s healthy: Purslane has the highest amount of heart-healthy omega-3 fats of any edible plant, according to researchers at the University of Texas at San Antonio. The scientists also report that this herb has 10 to 20 times more melatonin – an antioxidant that may inhibit cancer growth – than any other fruit or vegetable tested.

What makes a weed a weed? Or what makes it a “pervasive weed (the 7th worst, worldwide)” when it also is a nutritious food source?