There once was an evil wizard. He took 3 woman from their homes and turned them into rose bushes that looked exactly alike. He put them in his garden.
One of the woman had a husband and children and begged the wizard to let her see them.
He agreed. At night, he brought the woman to her house. In the morning he came and took her home.
One day the husband decided to go rescue her. So he snuck into the wizard's garden.
He looked and looked at the 3 identical rose bushes trying to figure out which could be his wife. Suddenly, he knew the answer and he took his wife home.
How did he know which rose bush was his wife?
The wizard brought the rosebush to her home at night and returned her to the garden in the morning. Therefore, she was the only plant without dew.