"Findings in both studies showed that the more silverleaf nightshade was mowed, the more it developed ways to avoid destruction, Kariyat said. The taproot went down further, nearly 5 feet deep, in the first generation of mowed plants. More spikes popped out on the stem as a defense against caterpillars feeding on the flowers. The flowers became more toxic to caterpillars, leading to less pressure from natural predators."