Bags of salad mix containing fresh spinach are seen on the shelf at United Market September 15, 2006 in San Rafael, California. (Justin Sullivan/Getty Images)
It's hard for laymen to tell the difference from rocket," said a Plus spokeswoman on Tuesday.
"We immediately took all affected bags off the shelves."
Samples were sent to the University of Bonn for testing, which detected more than 2,500 micrograms of poison—2,500 times more than the recommended daily allowance—in 150 grams of salad, German media reported.
Minister for consumer protectionism in the western state of Rhineland-Palatinate, Margit Conrad, warned shoppers to be vigilant.
"Not everything that looks like fruit and vegetable is edible," she said in a statement on Wednesday.
"No one should eat plants or parts of plants that have an unusual taste."










