The Tree on Riverside Drive

Every morning for thirty-seven years, Margaret Chen walked the same half-mile stretch along Riverside Drive in Chattanooga, Tennessee. She knew every tree on that path. But one silver maple held her attention more than the rest. It stood just six feet from the bank of the Tennessee River, its roots drinking deeply from the water table below. While other trees along the boulevard suffered during the drought of 2007 — leaves curling brown by July, branches cracking in August — that silver maple stayed lush and green.…