This in from Berlin: A shopper buying a bag of salad in a Hanover, Germany, supermarket discovered a poisonous weed mixed into his mixed salad. Fortunately the shopper knew his plants, and was able to discern the difference between rocket and the stems of senecio vulgaris, also called common groundsel, that were in the bag.
Common groundsel is a weed, an annual in the sunflower family, that grows in climates like northern Europe and much of the US, including, according to the University of California Integrated Pest Management Program, “nearly everywhere in California.” It's problematic for both people and grazing livestock, as it contains toxins, pyrrolizidine alkaloids, which can cause liver damage.
The bags of salad at the Plus discount supermarket store in Hanover were immediately taken off the shelves and sent to the University of Bonn for testing. German media reported that more than they found “2,500 micrograms of poison — 2,500 times more than the recommended daily allowance — in 150 grams of salad.” (The recommended daily allowance would, I guess, be none.)
“Not everything that looks like fruit and vegetable is edible,” said Margit Conrad, Minister for consumer protectionism in the western state of Rhineland-Palatinate. True. Which underscores the importance of knowing your food–although you shouldn't have to be a botanist to shop your local produce aisle safely–and where it comes from. The difference between a weed (stinging nettles, say, or purslane, which the FDA lists as the world's 7th most pervasive weed) and a boutique salad green is often just semantic anyway.