USDA PLANTS Database
The PLANTS Database provides standardized information about the vascular plants, mosses, liverworts, hornworts, and lichens of the U.S. and its territories. Search over 40,000 plant images of US plants.
Botany.com
Botany.com offers an encyclopedia of flowers and plants and resources to help people learn how to identify any different kinds of plants.
Other Botany Reference Links:
Virtual Library of Botany
Look at various botanical resources coving everything from Agriculture to Biophysics, sponsored by the University of Oklahoma.
NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.