After a corpse flower opened at the New York Botanical Garden (NYBG) last summer, drawing 30,000 visitors in the course of its brief and pungent bloom, it received the posthumous honor of becoming the three millionth specimen digitized from the Bronx institution’s herbarium. While NYBG is among New York City’s great green wonders, it’s also home to the world’s second-largest herbarium, created just after the garden was established in 1891. The William and Lynda Steere Herbarium now houses 7.8 million plant and fungal specimens, representing biodiversity from every continent. But what is a herbarium, you might ask, and why does it matter?