Sistem iki kasediakaké kanthi online ing loro situs. yakuwi, ing "Center for the Study of Digital Libraries Texas A&amp;M" (CSDL, Texas). lan ing "1999 lecture notes by J.L. Reveal, at that time a professor at the Norton Brown Herbarium, University of Maryland" (1, 2, 3; with an extensive listing of synonyms, both nomenclatural and taxonomic, for each name in the system). According to the latter site the main groups in the system are: