Christina- I'm afraid the information you're looking for is indeed hard to find. Many species and varieties were introduced commercially without government participation or notice, especially before about 1900. Old seed and nursery catalogs are potential sources of information, but they are ephemeral and have been preserved in scattered, hit-or-miss fashion; they rarely state accurately whether the plants are new to the continent.
If a plant had any conceivable agricultural or horticultural application, it may have been introduced by the USDA Office of Foreign Seed and Plant Introduction. See http://specialcollections.nal.usda.gov/products/conservation for an entree into their papers and related material. More may be available through the National Archives. I look forward to seeing what you come up with, but it's definitely going to require some legwork. Matthew K Chew Assistant Research Professor Arizona State University School of Life Sciences ASU Center for Biology & Society PO Box 873301 Tempe, AZ 85287-3301 USA Tel 480.965.8422 Fax 480.965.8330 [email protected] or [email protected] https://cbs.asu.edu/people/chew-0<http://cbs.asu.edu/people/profiles/chew.php> http://asu.academia.edu/MattChew
