''Ulmus laciniata'' var. ''nikkoensis'' Rehder, the Nikko elm, was discovered as a seedling near

Lake Chūzenji , also called Sea of Happiness, is a scenic lake in Nikkō National Park in the city of Nikkō, Tochigi Prefecture, Japan. It was created 20,000 years ago when Mount Nantai (2484 m) erupted and blocked the river. The lake has a surface area of 11 ...

, near

Nikkō is a city located in Tochigi Prefecture, Japan. , the city had an estimated population of 80,239 in 36,531 households, and a population density of 55 persons per km2. The total area of the city is . It is a popular destination for Japanese and ...

, Japan, and obtained by the Arnold Arboretum in 1905. The taxonomy of the tree remains a matter of contention, and has been considered possibly a hybrid of ''U. laciniata'' and ''U. davidiana'' var. ''japonica''. However, in crossability experiments at the Arnold Arboretum in the 1970s, ''U. laciniata'', a

protogynous Sequential hermaphroditism (called dichogamy in botany) is a type of hermaphroditism that occurs in many fish, gastropods, and plants. Sequential hermaphroditism occurs when the individual changes its sex at some point in its life. In particular, ...

species, was found to be incompatible with ''U. davidiana'' var. ''japonica'', which is

protandrous Sequential hermaphroditism (called dichogamy in botany) is a type of hermaphroditism that occurs in many fish, gastropods, and plants. Sequential hermaphroditism occurs when the individual changes its sex at some point in its life. In particular, ...

. Significantly, the variety was not recognized by Ohwi, though his reasons are not clear.

Kew Kew () is a district in the London Borough of Richmond upon Thames. Its population at the 2011 census was 11,436. Kew is the location of the Royal Botanic Gardens ("Kew Gardens"), now a World Heritage Site, which includes Kew Palace. Kew is a ...

's 'Plants of the World Online' treats var. ''nikkoensis'' as a synonym of ''U. laciniata''.

Description

Var. ''nikkoensis'' is a small tree; the specimen at the

Morton Arboretum The Morton Arboretum, in Lisle, Illinois, United States, is a public garden, and outdoor museum with a library, herbarium, and program in tree research including the Center for Tree Science. Its grounds, covering 1,700 acres (6.9 square kilometres ...

likened to a cherry tree. The tree is chiefly distinguished by leaves which are red on emergence, and toothed but not lobed as in the species. The perfect

apetalous Petals are modified leaves that surround the reproductive parts of flowers. They are often brightly colored or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''corolla''. Petals are usually ...

wind-pollinated flowers appear in March in England. File: Ulmus laciniata var nikkoensis leaves.JPG, var. ''nikkoensis'' leaves, Kew File:RN U. laciniata var. Nikkoensis leaf.jpg, var. ''nikkoensis'' leaf and scale

Pests and diseases

Heybroek found the tree provided 'relatively resistant' (to DED) progeny in the Dutch elm breeding programme.

Cultivation

There are no known

cultivar A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture ...

s of this taxon, nor is it known to be in commerce beyond the United States. File:RN Ulmus laciniata var. Nikkoensis (kew gardens london).jpg, ''Ulmus laciniata'' var. ''nikkoensis'',

Kew Gardens Kew Gardens is a botanic garden in southwest London that houses the "largest and most diverse botanical and mycological collections in the world". Founded in 1840, from the exotic garden at Kew Park, its living collections include some of the ...

Etymology

Var. ''nikkoensis'' is named for the

Nikkō National Park is a national park in the Kantō region, on the main island of Honshū in Japan. The park spreads over three prefectures: Tochigi, Gunma and Fukushima, and was established in 1934. History The establishment of Nikkō National Park dates ...

near the city of

, 125 km north of

Tokyo Tokyo (; ja, 東京, , ), officially the Tokyo Metropolis ( ja, 東京都, label=none, ), is the capital and List of cities in Japan, largest city of Japan. Formerly known as Edo, its metropolitan area () is the most populous in the world, ...

Accessions

;North America * Arnold Arboretum, US. Acc. no. 17908, collected wild in Japan. *

Dawes Arboretum The Dawes Arboretum is a nonprofit arboretum located in Newark, Ohio. It includes nearly of plant collections, gardens and natural areas. The site includes approximately 12 miles (19 km) of hiking trails and roadways for a four-mile (6&nbs ...

US.

Newark Newark most commonly refers to: * Newark, New Jersey, city in the United States * Newark Liberty International Airport, New Jersey; a major air hub in the New York metropolitan area Newark may also refer to: Places Canada * Niagara-on-the ...

Ohio Ohio () is a state in the Midwestern region of the United States. Of the fifty U.S. states, it is the 34th-largest by area, and with a population of nearly 11.8 million, is the seventh-most populous and tenth-most densely populated. The sta ...

, US. 2 trees, no acc. details available. *

, US. Acc. no. 180–84, received 28 February 1978 as scions from Arnold Arboretum (their accession #17908-D); 9 m tall in 2006. ;Europe *

Grange Farm Arboretum The Grange Farm Arboretum is a small private arboretum comprising 3 hectares accommodating over 800 trees, mostly native and ornamental species or cultivars, notably oaks, ashes, walnuts and elms, growing on a calcareous loam.Ostler, J. (2009) ...

Sutton St James Sutton St James is a village and civil parish in the South Holland district of Lincolnshire, England, about south-west of Long Sutton. Lying in the Lincolnshire Fens, Sutton St James did not exist at the time of the 1086 ''Domesday Book''. Su ...

, Spalding,

Lincolnshire Lincolnshire (abbreviated Lincs.) is a Counties of England, county in the East Midlands of England, with a long coastline on the North Sea to the east. It borders Norfolk to the south-east, Cambridgeshire to the south, Rutland to the south-we ...

, UK. Acc. no. 515 *

Royal Botanic Gardens, Kew Royal Botanic Gardens, Kew is a non-departmental public body in the United Kingdom sponsored by the Department for Environment, Food and Rural Affairs. An internationally important botanical research and education institution, it employs 1,10 ...

, UK. Acc. no. not known. *Great

Fontley Funtley – from the Anglo-Saxon, "Funtaleg", "spring field (clearing)", is a hamlet or exurb north of Fareham, Hampshire, England. It forms a projection towards the South Downs National Park and is generally included within Fareham's populat ...

Farm, Fareham, UK, '' Butterfly Conservation'' Elm Trials plantation, Home Field (4 specimens, 'Putatives' above), Platt (1 specimen), all planted 2002, grown from seed collected Liaoning, China, collected by Dr George Ware, Morton Arboretum, Lisle, Illinois, US.

Putative specimens

Trees at Great Fontley, Fareham, in southern England, grown from seed sent from Morton Arboretum and reputedly sourced in Liaoning Province, China, that were thought for many years to be '' Ulmus davidiana'', have fruit and short petioles inconsistent with that species, but matching descriptions and photographs of ''

Ulmus laciniata ''Ulmus laciniata'' (Trautv.) Mayr, known variously as the Manchurian, cut-leaf, or lobed elm, is a deciduous tree native to the humid ravine forests of Japan, Korea, northern China, eastern Siberia and Sakhalin, growing alongside ''Cercidiphyllu ...

''. Their leaves, to date (2023) lacking long extra tips, recall those of var. ''nikkoensis''.Brookes, A. H. (2020). ''Great Fontley Elm Trial, 2020 Report''. Butterfly Conservation,

Lulworth Lulworth is the popular name for an area on the coast of Dorset, South West England notable for its castle and cove. However, there is no actual place or feature called simply "Lulworth", the villages are East and West Lulworth and the coastal f ...

, England. In trials conducted by '' Butterfly Conservation'', the specimens at Great Fontley often grew too rapidly in the comparatively benign conditions, the narrow stem unable to bear the weight of the burgeoning crown, leaving the tree arching to the ground. The same trees commenced flowering when aged nine years, in mid-March.Brookes, A. H. (2022). ''Great Fontley Elm Trial, 2022 Report''. Butterfly Conservation,

, England. They were defoliated at the crown by DED when only 6 years old and < 4 m (13 ft) high, but recovered. They were, however, heavily afflicted by

slime flux Slime flux, also known as bacterial slime or bacterial wetwood, is a bacterial disease of certain trees, primarily elm, cottonwood, poplar, boxelder, ash, aspen, fruitless mulberry and oak. A wound to the bark, caused by pruning, insects, poo ...

during the exceptional drought of summer 2022; the only elm at Great Fontley to be so. File:Morfeo 025.jpg, Emergent leaves, Great Fontley elm, grown from seed sent from Morton Arboretum File:Davidiana leaves.jpg, Same, leaves in midsummer File:Seed Ulmus davidiana.jpg, Samarae of same (2021) File:Bark of David Elm Ulmus davidiana.jpg, Same, bark of 30-year-old tree (2020) File:U. davidiana closed canopy.jpg, Closed canopy of Great Fontley tree, casting heavy shade File:David & Japanese elm leaves.jpg, Leaves of Great Fontley elm (left) and Japanese Elm (right) for comparison

References

{{Taxonbar, from=Q7879495 laciniata var. nikkoensis Flora of Japan Trees of Japan Trees of Asia Ulmus articles with images Elm species and varieties Taxa named by Alfred Rehder