- AGRICOLA, National Agricultural Library bibliographic database
- USDA Plant Database,The PLANTS Database provides standardized information about the vascular plants, mosses, liverworts, hornworts, and lichens of the U.S. and its territories.
- Digital Atlas of the Virginia Flora, maintained by the Virginia Tech Department of Biology/Virginia Botanical Associates.
- Flora of the Washington-Baltimore Area, from the Department of Systematic Biology/Botany of the Smithsonian Institution.
- Flora of the Washington-Baltimore Area - Checklist (PDF, 605 KB), from the Smithsonian Institution.
- Flora of the Washington-Baltimore Area: DC Herbarium, in the Smithsonian Institution.
- NCU Flora of the Southeastern United States, Herbarium of the University of North Carolina at Chapel Hill.
- Flora of North America, The Flora of North America Editorial Committee. To directly access the on-line flora, go to http://www.efloras.org/flora_page.aspx?flora_id=1.
Links to botanical dictionaries
Native Plants Journal, a cooperative effort of the USDA Forest Service and the University of Idaho, to provide technical and practical information on the growing and planting of North American native plants.
BLM Publication 1730-1: Measuring and Monitoring Plant Populations. Huge file to download (PDF, ~5.1 MB). View BLM technical references list., which also has information on how to order hard-copies of publications.
The Flora of Virginia Project
Biota of North America Program (BONAP)