The hybrid elm cultivar Ulmus × hollandica 'Superba' is one of a number of intermediate forms arising from the crossing of the Wych Elm U. glabra with a variety of Field Elm U. minor. Boulger tentatively (1881) and Green more confidently (1964) equated it with a hybrid elm cultivated in the UK by Masters at Canterbury in the early 19th century, known as "Masters' Canterbury Seedling" or simply the Canterbury Elm. Loudon examined a specimen sent by Masters and considered it a hybrid, calling it U. montana glabra major (not to be confused with U. major Smith, U. × hollandica 'Major').