Holding more than 250,000 specimens, and growing at a rate of approximately 10,000 specimens each year, the lichen herbarium of The New York Botanical Garden is the largest in the western hemisphere and one of the premier such collections worldwide. As is the case for other cryptogam groups (algae, bryophytes, fungi), devoted study and collection of lichens at the Garden has its roots in founding of the institution more than century ago. The nucleus of the collection was formed at that time as founders Nathaniel L. Britton and Elizabeth G. Britton, together with other Garden scientists and collaborators, collected lichens extensively during expeditions throughout North America and the New World Tropics.

The size and scope of the collection has expanded significantly within the last four decades as Richard C. Harris, and later James C. Lendemer, joined the staff of the Garden. As a result of their work research focuses, the collection has a particular strength in traditionally understudied crustose lichen groups from the New World, with an emphasis placed on the lichens of eastern North America. In addition to the collections of Garden scientists and students, the Garden has committed to curating and preserving the wealth of information accumulated by lichen specialists through the incorporation of the collections of Jonathan Dey (30,000 collections, focus on macrolichens of North America, especially Appalachia), Elisabeth Lay (17,000 collections, focus on eastern North America) and Clyde Reed (20,000 collections, focus on Mid-Atlantic Region eastern North America) among others.