The MBLWHOI Library Herbarium, originally part of the George M. Gray Museum, documents the flora of Cape Cod, Massachusetts and associated coastal islands. The collection contains more than 2000 non-vascular and 7000 vascular plant specimens.
The vascular plant collection, representing Barnstable, Dukes and Nantucket Counties, dates back to 1900. Major contributions were made in the early 1900's by three eminent Pennsylvania botanists. Francis Whittier Pennell came to the MBL in the summer of 1911 upon graduation from the University of Pennsylvania and put hundreds of sheets into the vascular plant collection. Pennell later became head of the Botany Department of the Academy of Natural Sciences of Philadelphia. John Milton Fogg, Jr., who wrote his Ph.D. thesis on the flora of the Elizabeth Islands (1930) under Harvard botanist M.L. Fernald, contributed many beautifully made sheets from those islands and from Falmouth. Edwin T. Moul, Professor of Botany at Rutgers University and a specialist in the study of coastal wetlands plants, made contributions over several decades. Significant acquisitions resulted from the 1923 and 1947 Penikese Island surveys by Fogg and Moul respectively.
In the latter part of the 20th century local amateur and professional botanists, engaged in inventories of critical wildlife and plant habitats, contributed several hundred specimens. Dr. Richard H. Backus, Herbarium Curator Emeritus, contributed much of the most recent material and spearheaded the 1999 Penikese Island Survey, which yielded about 400 new sheets. Other important accessions were gifts of more than 500 sheets of Nantucket and Martha's Vineyard specimens from the New England Botanical Club Herbarium at Harvard University, and a set of former Massachusetts State Botanist Bruce Sorrie’s specimens collected from this area.
To quote Dr. Backus, the botanical record contained within the MBLWHOI Library Herbarium plays a vital role "in helping to document floral and environmental changes and in locating and protecting rare plants and their habitats." The Herbarium has a critical mission given the global significance and rarity of certain plant communities on Cape Cod and the Islands.