 Henry (1913), referring his readers to an account of the Kew specimen in the journal "Woods and Forests", 1884, suggested that it may have originated from a witch's broom.It is usually classified as a form of "Ulmus glabra" and is known widely as the 'Dwarf Wych Elm'.However, the ancestry of 'Nana' has been disputed in more recent years, Melville considering the specimen once grown at Kew to have been a cultivar of "Ulmus × hollandica".