Bill Burk, the botany librarian at the Couch Biology Library at the University of North Carolina at Chapel Hill, discusses the morel mushroom. This mushroom is an elusive delicacy that cannot be purchased in most grocery stores and it is particular about its habitat. It won't grow if it's too hot, too dry, too wet, or too cold. People seek it from Oregon's mossy forests to North Carolina's hardwoods. Restaurant gourmands know that morels promise an aromatic meal, but they come with a danger. Morels have imposters, and these imposters can kill. To dine safely, ask an expert.