Thinking about plants in winter recently, I remembered a particular good-sized cottonwood I saw while walking along a riverbank. What was its story? From James Halfpenny’s fascinating book “Winter: An Ecological Handbook,” I learned that cottonwoods, like many northern trees, have very special adaptations to survive the long, cold winters. They begin their “hardening” process in the fall, as temperatures begin to drop and the amount of daylight decreases. Leaves typically fall during this stage