Patuxent Research Refuge, Maryland (USFWS-PRR)

PRR is the reference herbarium for plants occurring on the Patuxent Research Refuge. The refuge was established in 1936 by executive order of President Franklin D. Roosevelt and is the nation's only national wildlife refuge established to support wildlife research. It is located between Washington and Baltimore.

When the refuge was established in 1936, botanist Neil Hotchkiss and other scientists surveyed the flora on the 2,650 acres which made up the Refuge. Lists of plants found on the Refuge were published in 1940 and 1947. The latter list tabulated 877 plant taxa. Voucher specimens were collected and reposited in the Refuge's herbarium. By 1980, when the refuge expanded to 4,741 acres, a total of 969 plant taxa were listed.

In the early 1990's as part of the Base Re-alignment and Closure (BRAC) process, the Department of Defense transferred about 8,100 acres of land from Fort Meade to the Department of Interior, with control of the land given to the Fish and Wildlife Service. The addition of this parcel, now known as the North Tract, brought the total acreage of the Refuge to over 12,800 acres.

A floral survey of the North Tract began in 2010 and a re-survey of the older parcel of the Refuge, known as the Central and South Tracts, was initiated in 2013. As of October 2019, the herbarium holds over 5,200 voucher specimens from over 1,250 taxa found on the Refuge. This includes some Maryland rare, threatened, and endangered (RTE) species and at least five species new to Maryland. Some duplicate and unique voucher specimens are held by other herbaria.

With the collaboration of the Norton-Brown Herbarium at the University of Maryland, and the Mid-Atlantic Consortium the herbarium is digitizing its voucher specimens collection. Recently, the herbarium has added lichens to its collection.

Please feel free to peruse the herbarium's data, but use it with caution as we are still tweaking things.

For more information
Contacts: Bill Harms (
Collection Type: Preserved Specimens
Management: Live Data managed directly within data portal
Global Unique Identifier: a3a739d8-2d85-4834-af69-5939f0160ad3
Digital Metadata: EML File
Access Rights: The database records found here may be used by researchers for non-commercial purposes. If any of these records are used in an analysis, report or publication, the provenance of the original data must be acknowledged and the PRR Herbarium notified.
Patuxent Research Refuge
230 Bald Eagle Drive
Laurel, MD   20708
Collection Statistics
  • 5,327 specimen records
  • 5,281 (99%) georeferenced
  • 4,866 (91%) with images (7,697 total images)
  • 5,156 (97%) identified to species
  • 149 families
  • 561 genera
  • 1,076 species
  • 1,290 total taxa (including subsp. and var.)
Extra Statistics