题干
Can plants learn and remember? Monica from Australia thinks so.
Monica and her team members did some tests on mimosas(含羞草). The plants close their leaves quickly when people touch them. They put some mimosas in 56 pots. Every time they dropped the pots from 30cm high, the plants closed their leaves. Monica and her team members did this for a whole day. To their surprise，at the end of the day, the plants didn't close their leaves at all. It seemed that the plants learned that this action wouldn't hurt them.
Another amazing thing was that the plants might remember things for a long time. Monica dropped the same pots of mimosas four weeks later. The plants still didn't close their leaves.
Monica wasn't sure how plants learned and remembered. "The plants don't have brains, after all. Maybe they learn and remember with the help of their cells(细胞)," she said.