Ulmus × hollandica var. insularum
 Ulmus × hollandica var. insularum was recognized as a biometrically distinct population of U. × hollandica endemic to all the Channel Islands and the Cotentin peninsula of France by Richens and Jeffers in 1975 The tree had been treated within U. montana (:glabra) until McClintock correctly assigned it to U. × hollandica.