The

American elm ''Ulmus americana'', generally known as the American elm or, less commonly, as the white elm or water elm, is a species of elm native to eastern North America. The trees can live for several hundred years. It is a very hardy species that can ...

cultivar A cultivar is a kind of Horticulture, cultivated plant that people have selected for desired phenotypic trait, traits and which retains those traits when Plant propagation, propagated. Methods used to propagate cultivars include division, root a ...

''Ulmus americana'' 'Ascendens', 'Upright American Elm', was cloned c.1910 by Bernard H. Slavin, Superintendent of Parks, Rochester,

New York New York most commonly refers to: * New York (state), a state in the northeastern United States * New York City, the most populous city in the United States, located in the state of New York New York may also refer to: Places United Kingdom * ...

, from a tree growing in

Seneca Park Seneca Park may refer to: * Seneca Park (Louisville, Kentucky), an Olmsted-designed park * Maplewood Park, an Olmsted-designed park in Rochester, New York, listed on the National Register of Historic Places as "Seneca Park West" * Seneca Park, an ...

, Rochester, and named in 1927 for its narrow oval form.Malcolm A. Milne & Jacob Gerling, 'Improved elm is upright form', ''Trees Magazine'', September-October 1941, Vol.4, No.5, p.9; Santa Monica, California
/ref> See also the similar cultivars 'Columnaris' and 'Augustine Ascending'. It is not known why such a promising clone as 'Ascendens' appears rare in cultivation, but 'Augustine Ascending' was released at about the same date. Neither

Green Green is the color between cyan and yellow on the visible spectrum. It is evoked by light which has a dominant wavelength of roughly 495570 nm. In subtractive color systems, used in painting and color printing, it is created by a com ...

nor Santamour suggested that they were synonyms.

Description

The tree has small, fastigiate lateral branches forming a narrow, oval head. Its leaves are similar in shape and texture to those of the parent species, but slightly smaller. Arnold Arboretum, however, report leaves 3 to 6 in. long and 2 to 4 in. wide. The bark remains smooth for longer than usual in the species and its fissures are less deep, while the trunk lacks the marked buttressing of the species.

Pests and diseases

The clone's resistance to Dutch Elm Disease is not known, but the species is highly susceptible to the disease and Elm Yellows; it is also moderately preferred for feeding and reproduction by the adult Elm Leaf Beetle ''

Xanthogaleruca luteola ''Xanthogaleruca luteola'', commonly known as the elm-leaf beetle, is a beetle species in the family Chrysomelidae that is native to Europe but invasive in other parts of the world.http://cisr.ucr.edu/elm_leaf_beetle.html - Center for Invasive ...

'', and highly preferred for feeding by the Japanese Beetle ''

Popillia japonica The Japanese beetle (''Popillia japonica'') is a species of scarab beetle. Due to the presence of natural predators, the Japanese beetle is not considered a pest in its native Japan, but in North America and some regions of Europe, it is a no ...

'' in the United States. ''U. americana'' is also the most susceptible of all the elms to

verticillium wilt Verticillium wilt is a wilt disease affecting over 350 species of eudicot plants. It is caused by six species of '' Verticillium'' fungi: ''V. dahliae'', ''V. albo-atrum'', ''V. longisporum'', ''V. nubilum'', ''V. theobr ...

.Pegg, G. F. & Brady, B. L. (2002). ''Verticillium Wilts''. CABI Publishing.

Cultivation

In an article on the cultivar, ''Trees Magazine'' (Sept.-Oct. 1941), observing of American elm that there were "too many city streets where sidewalks are upheaved by its heavily buttressed trunk, lawns impaired by its massed tops, and roofs overhung by upper branches brushing the gables of homes," described 'Ascendens' as, by contrast, "an ideal variety for the narrow streets of our cities and for small-area planting". The tree was much planted in the Rochester area. It was described as hardy and less prone to wind-damage than broader forms. The tree is not known to have been cultivated beyond the US.

Accessions

North America

Arnold Arboretum The Arnold Arboretum is a botanical research institution and free public park affiliated with Harvard University and located in the Jamaica Plain and Roslindale, Massachusetts, Roslindale neighborhoods of Boston. Established in 1872, it is the ...

, US. Acc. no. 140-61.

References

{{Elm species, varieties, hybrids, hybrid cultivars and species cultivars , state=collapsed American elm cultivar Ulmus articles missing images Ulmus