Leaves of three, let them be! Today’s Please Explain is all about poisonous plants. We're joined by Dr. Michael J. Balick, Vice President for Botanical Science and Director and Philecology Curator at The New York Botanical Garden Institute of Economic Botany, and Dr. Lewis Nelson, Associate Professor of Emergency Medicine at New York University School of Medicine, and Director of the Fellowship in Medical Toxicology at New York University School of Medicine and the New York City Poison Control Center.