Flora ID Northwest – Illustrated databases for All The Native and Naturalized Plants in Washington, Oregon, California, Idaho, Nevada, Utah, Wyoming, Montana, Colorado, North Dakota, South Dakota, Nebraska, Kansas, Minnesota, Iowa as well as the Canadian provinces of British Columbia, Alberta, Saskatchewan, and Manitoba.

M.U.D.E.S. – Miami University Dendrology Expert System, Identification of Trees and Woods of the North Central United States

Old World Crataegus Identification – This database is intended as a supplement to my paper: Christensen, K.I. 1992. Revision of Crataegus Sect. Crataegus and C. Nothosect. Crataeguineae (Rosaceae-Maloideae in the Old World. – Syst. Bot. Monogr. 35: 1-199. Knud Ib Christensen >Assoc. Prof., lic. scient. (Ph.D.) >Botanic Garden > University of Copenhagen > Oester Farimagsgade 2B >DK-1353 Copenhagen K >Denmark > Tel. +45 3532 2224 or +45 3532 2217 -

California Weed Identification – A variety of books and CDs authored by Dr. Joe DiTomaso for the identification of weeds in California and other western states