ITEX research was begun to develop generalizations on the growth of tundra plants through synthesis of data from distant arctic and alpine sources gathered by strict protocols. Target species have been selected from among widely distributed ones with attention to those without serious unresolved taxonomic problems, since valid comparisons and generalizations rest on data reported consistently from the same species. The consortium of researchers must firmly establish the identity of the experimental subjects to preserve the integrity of the ITEX synthesis. Documentation is possible only when voucher specimens are conserved. Notes on taxonomy and biology are provided as background for 14 primary, five secondary, and three additional candidate ITEX species.