Hybrid parentage U. glabra × U. minor Origin Belgium | Cultivar 'Superba' | |
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The hybrid elm cultivar Ulmus × hollandica 'Superba', once commonly known in the UK as the Canterbury Elm, is one of a number of hybrids arising from the crossing of the Wych Elm U. glabra with a variety of Field Elm U. minor. It was identified by Morren as U. montana (: glabra) var. superba in 1848, Morren having adopted the name 'Superba' from the Fulham nurseryman Osborn who supplied the trees. It was confirmed by Krüssmann in 1962 as a cultivar. Krüssman (1984) states that 'Superba' is synonymous with the former U. praestans .
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Description
'Superba', according to the full description in Elwes and Henry (1913), is a rapidly growing, narrow, pyramidal tree with smooth bark and steeply ascending branches. It bears large smooth biserrate leaves, 8–12 cm (3–4 in) long and 4–6 cm broad, very oblique at the base and similar to those of the Wych Elm, but with petioles 5–10 mm long. The flowers too resemble those of the Wych Elm. Krüssman (1984), who gives a leaf illustration, adds that the elliptic samarae are 1.5–2 cm long with the seed nearly central, that the leaves have 15–18 pairs of veins, and that the leaves are retained late into autumn.
Herbarium leaf-specimens suggest that more than one clone has been called U. × hollandica 'Superba' (see External links below).
Pests and diseases
The tree is very susceptible to Dutch elm disease.
Cultivation
'Superba' was cultivated in the UK by Masters at Canterbury in the early 19th century, where it became known as "Masters' Canterbury Seedling" or simply the "Canterbury Elm", and later, confusingly, as U. montana (: glabra) 'Major'. Morren states that 'Superba' was introduced to Belgium by Denis Henrard of Saint Walburge, Liège, that in 1848 it had been present in Belgium for only three years, and that this variety was the one described as 'Superba' by Osborn, whom Henrard had visited at his nursery in Fulham in September 1844. This suggests that 'Superba' was brought to Belgium from England. 'Superba' was reputed by Louis Späth to have been much valued as a street tree, notably in Magdeburg, Germany. A 1907 photograph shows an avenue of the tree in Magdeburg, described as U. praestans E. Schoch, a "hybrid between U. scabra [U. glabra] and U. campestris [U. minor]" - i.e. as a form of U. × hollandica. 'Superba' from the Späth nursery in Berlin was reintroduced to the UK at Kew Gardens in 1900, and remains represented by a specimen at Wakehurst Place donated in 1949; it survives by being treated as a hedging plant, too low to attract the attentions of the Scolytus beetles which act as vectors of Dutch elm disease. Three specimens supplied by Späth to the Royal Botanic Garden Edinburgh in 1902 as U. montana superba may survive in Edinburgh as it was the practice of the Garden to distribute trees about the city (viz. the Wentworth Elm); the current list of Living Accessions held in the Garden per se does not list the plant. An old narrowly pyramidal U. × hollandica with steeply ascending branches, which stands in Regent Road Park, Edinburgh (2016), has leaves that match the RBGE 1902 herbarium-specimen of U. montana superba (see External links below).
It is not known whether 'Superba' was introduced to North America. An elm described as 'Superba' obtained from Louis van Houtte in Belgium before 1841, and so pre-dating the introduction of 'Superba' to Belgium, was photographed at the Ellwanger and Barry nursery at Mount Hope, Rochester, New York, c. 1900. However, the photograph is also captioned 'Belgium Elm'. By 1915 this tree was considered "probably only a varietal form of U. glabra or another hybrid of that species".
Etymology
Morren states that 'Superba' was so called "parce qu'en effet cette variété l'emporte sur les autres par sa beauté" [:because indeed this variety surpasses others in beauty].