The William and Lynda Steere Herbarium is the centerpiece of the Garden's botanical research program. It is one of the largest herbaria in the world, and the largest in the Western Hemisphere. The Herbarium holds a collection of more than seven million preserved specimens filed according to a standardized system of classification. All groups traditionally considered plants –flowering plants, conifers, ferns, mosses, liverworts, and algae, as well as fungi and lichens– are represented in the Herbarium collection, which is particularly strong in specimens from the Americas. This reflects the emphasis of the research projects conducted by Garden researchers.