Tags: Cultivar (Cultivated Variety).
The American hybrid cultivar Ulmus ‘Frontier’ [1] is a United States National Arboretum introduction (NA 55393) derived from a crossing of the European Smooth-leafed or Narrow-leafed Elm Ulmus minor subsp. minor with the Chinese Elm Ulmus parvifolia in 1971. Released in 1990 the tree is a rare example of the hybridization of spring-flowering and autumn-flowering elms.