Though many spring flowers have bright advertisements offering sweet rewards to honeybees, some common flowers have not-so-sweet or even toxic nectars. Why plants would try to poison the honeybees they wish to attract is a scientific mystery. The honeybee, which accounts for the pollination of at least 1/3 of the world’s crop plants, may encounter such poisoned nectar in common crop and garden plants such as Rhododendrons and almond trees.