The MBLWHOI Library Herbarium (SPWH), formerly the Marine Biological Laboratory Herbarium, documents the flora of Cape Cod, Massachusetts and adjacent islands. The collection, dating back to the 1850's, consists of approximately 7,000 vascular and 2,000 non-vascular plant specimens. The non-vascular collection consists primarily of marine algae of Cape Cod and the Islands. The Digital Herbarium is a fully searchable database of specimen images and data, serving as an online compendium of the marine, freshwater and terrestrial flora of Cape Cod and the Islands. This work has been supported, in part, by a grant from the Woods Hole Oceanographic Institution Sea Grant Program, Project No. A/S-47-PD. Digitization of the marine algae collection is a joint project with the Northeast Algal Society. Current taxonomy, authorities and species biological data, including descriptions of geographic range, habitat and seasonality, are taken from the NEAS Keys to Benthic Marine Algae of the Northeastern Coast of North America from Long Island Sound to the Strait of Belle Isle ©. The MBLWHOI Library would like to thank NEAS and James Sears for kindly granting us permission to use this data. © Copyright MBLWHOI Library