National (International) Data Portals:
These five sites compile data from herbaria across the United States.

Webmaster: Eric Ribbens
Regional Data Portals:
These are numerous sites that present herbarium data for different geographic areas of the United States. Some aggregate data for a particular multi-state region, some aggregate data for a state, and some are individual herbarium data portals.
Taxonomic Data Portals:
These sites present herbarium data for specific taxonomic groups: algae, fungi, bryophytes, lichens, and others.
The U.S. Virtual Herbarium Project: Guide to Data Portals.

A list of websites that offer searchable access to herbarium specimen data. Please report changes, corrections, or additions to Eric Ribbens.
About Us
The U.S. Virtual Herbarium Project:
Bringing all herbaria into a digital network and demonstrating the value of shared information.