Ulmus 'Hamburg'

The hybrid elm cultivar Ulmus 'Hamburg' was originally raised by the Plumfield Nurseries, Fremont, Nebraska, circa 1932, after its discovery by Mr. Lloyd Moffet in a bed of Siberian Elm Ulmus pumila seedlings from Tekamah.^[1] It was later marketed by Interstate Nurseries, Hamburg, Iowa, from 1948, as 'Interstate's New Hamburg Hybrid Elm'. Green stated that it was originally said be a hybrid of Ulmus pumila (female parent) and Ulmus americana,^[2] but the Hamburg Nurseries of Iowa made no such claim for it in their catalogues from 1948 onwards.^[3][4][5] It is now considered more likely that Ulmus rubra was the male parent, as it was also known as 'Hybrid Chinese Elm',^[2] and therefore probably synonymous with Plumfield Nurseries' 'Hybrid elm' of the same date, a known crossing of U. pumila and U. rubra,^[6][7] – and so, perhaps, also synonymous with Ulmus × intermedia 'Fremont', an elm of the same parentage found a little later in Plumfield Nurseries.

An U. pumila × U. rubra parentage would, by present classification, make the cultivar Ulmus × intermedia 'Hamburg' .

A similar erroneously conjectured crossing with U. americana occurred at Plumfield Nurseries in the 1930s, with their so-called "Wheatley hybrid elm" (apparently not the European 'Wheatley'), briefly marketed in 1934: "Our variety, an attractive round-headed rapid growing tree, with medium sized glossy leaves; originally imported from Holland and hybridized with American white elm, Ulmus americana ".^[8]

Description[edit]

'Hamburg' has been described as a hardy, very rapid grower, with much stronger branching than the Siberian Elm.^[9][10] Hamburg Nurseries described it as "a shapely tree with large, dark green leaves".^[5] Leaves 3 to 4.5 inches long, 1.5 to 2 inches wide.^[11]

Pests and diseases[edit]

'Hamburg' had not (by 1995) been widely tested for resistance to Dutch elm disease.^[9]

Cultivation[edit]

Largely confined to the United States, several were introduced to the UK. A tree in Exeter University Botanic Gardens, Exeter, Devon, however, at one time listed as 'Hamburg Hybrid' (TROBI Champion, 17 m high, 55 cm d.b.h.), has since been found to be Ulmus laevis. 'Hamburg' is not known to have been introduced to Australasia.

Notable trees[edit]

Two well-grown specimens, planted in 1953 and therefore among the earliest specimens sourced from the Hamburg Nurseries, stand (2022) in Arnold Arboretum, Massachusetts, USA.^[11]

Synonymy[edit]

• 'Hamburg Hybrid Elm': Interstate Nurseries, Hamburg, Iowa, Catalogue, Spring 1949.
• 'Hybrid Chinese Elm': Plumfield Nurseries, Fremont, Nebraska.^[7]

Accessions[edit]

North America

• Arnold Arboretum, US. Acc. nos. 520–53, 666–50.

References[edit]