Large tree to 40 m, suckering. Young bark smooth, sandy to grey, then flaking in small, shallow scales in places to show the amber under-bark. Young twigs slender, very downy. Leaves 4–8 × 2–4 cm, ovate or oval, rounded or slightly cordate at the base, quite broadly pointed to rounded at the tip, with 7–11 major veins on each side each leading to a broad but shallow, round-shouldered tooth; upper surface very dark green with scattered hairs, lower surface variably pubescent; petiole short (c. 3 mm). Drupe c. 5 mm wide, ridged above. (Bean 1981).
Distribution Armenia Scattered populations in mountain forests. Azerbaijan Scattered populations in mountain forests. Georgia Scattered populations in mountain forests. Iran In mountain forests south of the Caspian Sea. Iraq One population in the northern mountains. Turkey Scattered populations in Anatolia.
Habitat Forests on moist but free-draining soils, open mountainsides, to 1550 m.
USDA Hardiness Zone 7
RHS Hardiness Rating H6
Conservation status Vulnerable (VU)
Although anyone reviewing the long list of synonyms published by early botanists for Zelkova carpinifolia might assume the opposite, this an easily recognised tree, growing to large sizes but with small, neatly oval leaves and a smooth bark that like other members of this genus flakes in very shallow scales to reveal here and there the brightly coloured underbark. The wild populations do in fact contain considerable genetic diversity, with western trees (from Anatolia and the Georgian Colchis) being particularly distinct from eastern ones (from Iran, Azerbaijan and eastern Georgia; Kozlowski & Gratzfeld 2013); this genetic split does not however fit well with the physical features used by Anşin & Gerçek in 1991 to differentiate ‘subsp. yomraensis’ from eastern Turkey (Royal Botanic Gardens, Kew 2023). A new population was discovered in the mountains of northern Iraq in 2022 (Uzun & Galalaey 2022).
Although these wild populations stretch across quite a wide geographical area, they are much fragmented, something which may have partly occurred during the last six millennia (Kozlowski & Gratzfeld 2013). The rate of forest loss across this area is increasing, due to logging and bovine grazing pressure, while Elm Disease, to which Zelkova is moderately susceptible, is identified as a threat in Iran (Ahmadi, Kavosi & Soltanloo 2014). The species is now assessed as Vulnerable (Kozlowski et al. 2018).
Zelkova carpinifolia is one of the largest trees in these forests, where it tends to occupy the best soils; some specimens may be 850 years old (Kozlowski & Gratzfeld 2013). The strong, durable timber is highly valued and the word ‘zelkova’ was derived by François André Michaux in 1831 from the Georgian name for the tree, which can be translated as ‘pillar of stone’ (Michaux 1831); in Iran it is called āzād, meaning ‘noble tree’ (Encyclopaedia Iranica 2023). In Azerbaijan the leaves and bark, additionally, are used for dyeing wool (Kozlowski et al. 2018).
Trees and Shrubs Online is concerned in particular with woody plants as they have been cultivated in north-western Europe, and in other zones with a comparable climate. In this respect, Zelkova carpinifolia is one of the most fascinating and also misrepresented of trees, justifying the unusually long and detailed discussion which follows. It was the first tree from the Caucasian biome to be grown in northern Europe, and is among the largest and most impressive exotics which can be cultivated here. All of the oldest surviving specimens in western Europe also seem to belong to a clone or clonal group whose remarkable upright habit makes it, along with the Lombardy Poplar Populus nigra ‘Italica’, perhaps the grandest of all fastigiate trees.
Among mature specimens in cultivation, this fastigiate sport is so preponderant that most European garden writers have simply assumed that this is the natural way the species grows, much as they spent many years assuming that the Persian Ironwood Parrotia persica was naturally inclined to form a tangled shrub growing much wider than tall, rather than the slender, small tree it becomes in native forests. (Another way of putting this is that, although ‘ordinary’ tree-shaped Zelkova carpinifolia can be found in cultivation quite widely, they may not readily be recognised as representing the same species, while it is the fastigiate ones that always seems bound to attract the interest of photographers and tree measurers.) In 2023, the Georgian version of Wikipedia illustrated its article on Z. carpinifolia not with a specimen from the country’s wild forests but with an example of the fastigiate variant photographed in Paris. Even Gregor Kozlowski and Joachim Gratzfeld in their superb monograph Zelkova – an ancient tree (Kozlowski & Gratzfeld 2013) repeat the misconception that ‘the vase-shaped crown and short, broad trunk dividing into numerous nearly erect, strong branches, give the species its characteristic and distinctive form.’ Zelkova – an ancient tree meanwhile offers a valuable resource in presenting many photos of Z. carpinifolia taken in its native forests, some of them pollarded or shredded but none them remotely resembling this cultivated genotype.
Naturally fastigiate trees do exist – the Japanese apple species Malus tschonoskii is a good example – while others, such as the Incense Cedar Calocedrus decurrens, adopt a more strictly fastigiate habit in northern Europe apparently in response to an unfamiliar microclimate; it is sometimes suggested that the tendency of these fastigiate zelkovas to produces masses of erect branches from a single point can be attributed to spring frost damage in youth (Hughes & Welton 2009), but it is really a very hardy tree, which leafs out quite late.
In fact the fastigiate specimens of Zelkova carpinifolia in western Europe differ so strikingly from the species’ normal method of growth, and resemble one another so strongly, that it makes much more sense to view them as clonally reproduced examples of a single sport. One observable variation is that some of these trees begin to produce their fastigiate branches from ground level, while others branch from a straight bole which may be as much as six metres long; these differences can readily be explained by the conditions in which the individual plant grew up, with long-boled trees such as the one in the Padua University Botanic Garden, Italy (monumentaltrees.com 2023) beginning life in close competition with other trees – and perhaps with the benefit of formative pruning – while multi-stemmed ones such as the example in the meadow below Kenwood House in London took advantage of, or were slightly stunted by, an open situation. One or two old specimens, including the famous tree on College Road in Dulwich, south London, lean at the base, but this is demonstrably due to heaving in long-forgotten storms. These fastigiate trees are accordingly described here, for the first time, as the cultivar ‘James Gordon’; see the cultivar entry below for a further discussion.
Fortuitously, a large genetic study of cultivated Zelkova carpinifolia was undertaken towards the start of Project Zelkova (Christe et al. 2014). The authors’ aim was to assess the diversity and representativeness of ex situ collections of the species and they sampled the DNA of many specimens in search of different haplotypes. They were not looking for – and may not have expected to find – clusters of clonally identically plants, but they did sample a good number of trees with the fastigiate appearance of ‘James Gordon’, all of which turned out to belong to the same (eastern) haplotype.
To recount the history of the progress of Zelkova carpinifolia from Iran to England is also to be reminded of the inevitable degree to which garden writers tend to repeat one another’s errors, rather than studying the earliest available sources for themselves: the text in W.J. Bean’s Trees and Shrubs Hardy in the British Isles unfortunately proves this point by stating that the species was ‘introduced to France in 1760’.
The earliest record of Zelkova carpinifolia in cultivation in the UK is provided by William Aiton in Hortus Kewensis (Aiton 1789): Aiton states that James Gordon first grew the tree in 1760, at his Mile End Nursery in east London. (He called the species ‘Ulmus nemoralis’, reminding us of the extent to which the early uncertainly surrounding the zelkova’s true nature may impede research.) Gordon was one of his generation’s most respected botanists, though he did not publish anything himself; he had been the first person in Britain and to grow Chinese trees such as Ginkgo biloba and Styphnolobium japonicum which had worked their way westwards across Europe, as well as the south-east European Tilia tomentosa (Aiton 1789), and he was the first European to import several North American trees, including Ulmus americana. Writing nearly a decade after Gordon’s death, Aiton also claimed that ‘Ulmus nemoralis’ was an American species – which can be taken to imply that Gordon did not happen to tell Aiton where he got his plants from, but not necessarily that Gordon himself was unaware of their Iranian origins. (An early planting of ‘James Gordon’ at Wardour Castle in Wiltshire was also locally believed to have been received from the United States in the seventeenth century (Elwes & Henry 1906–1913). It is practically inconceivable that Gordon could really have obtained his zelkova via a cultivated American source.)
Although Aiton was primarily interested in the cultivation of trees in what was to become the Royal Botanic Gardens at Kew, his reference to ‘Ulmus nemoralis’ does not mean that the species was planted at Kew in 1760. However, specimens at Kew described by John Loudon in the 1830s (this time under the name ‘Planera richardii’) were already so large that they must have been planted very soon after this date, and were presumably supplied by Gordon (Loudon 1838). These original trees were not, as most authors assume, the big examples of ‘James Gordon’ which currently grow at Kew near the Brentford Gate and in the private ‘Paddock’ behind the Library; in the early twentieth century the biggest specimens stood near the Order Beds and near the Main (Elizabeth) Gate, and have long gone. From their growth rates, the two largest survivors may be no older than another pair of ‘James Gordon’ in the Pagoda Vista, which are known to date from 1868 (Tree Register 2023).
In Arboretum et Fruticetum Britannicum Loudon also described trees at nearby Syon Park whose stature suggested that they must be about as old as the oldest at Kew (Loudon 1838). It is tempting to assume that the gigantic ‘James Gordon’ which still grows near the statue of Flora here is one of these originals, but this has grown so fast in the years since 1905 that it could be considerably younger (Tree Register 2023). However, the current rapid growth can probably be explained by this tree’s production of ‘reaction wood’ in response to the crown’s partial collapse in 2002. A similar response can be observed in an even bigger specimen of ‘James Gordon’ of unknown origin growing in what is now the suburbs of Worlingham in Suffolk; this was pollarded in 2016 after dropping a branch on an adjacent bungalow, when its girth was just eight metres (Tree Register 2023). Loudon’s 1830s portrait of one of the zelkovas at Syon was engraved in summer, when the dense foliage conceals the characteristic branch structure of ‘James Gordon’, but its outline is typical for a mature tree of this clone (Loudon 1838).
In France, François André Michaux published a brief monograph Mémoire sur le Zelkoua, Planera Crenata in 1831. Michaux was unaware of the tree’s history in England, but states with some confidence that the largest and oldest in France, Italy or Germany was one grown by Louis-Guillaume Lemonnier at his private arboretum near Fontainebleau in France, which was destroyed along with the garden around 1820 when it was 23 m tall (Michaux 1831). Michaux estimated that this tree had been planted in or before 1765, while Lemonnier had not begun his arboretum until c.1762 (Jacobsohn 2012). All this makes it seem unlikely that Gordon could have sourced his zelkovas from a cultivated population on the near continent, but very likely that the continental population had itself originated from Gordon’s nursery.
Michaux states that ‘many’ zelkovas were planted by the Comte de Dijon at the Château de Poudenas in south-west France in 1789 (Michaux 1831). In the 1830s, a single survivor here was portrayed in winter for Arboretum et Fruticetum Britannicum (Loudon 1838) and is clearly ‘James Gordon’. The length of its bole is unusual – Lemonnier’s tree was also described by Michaux has being clean-boled for six metres – but this would be a natural feature if the ‘many’ original trees had been set in a close plantation, or if the survivor had benefitted from high pruning – a task which the Comte’s foresters are likely to have undertaken in the case of a tree rumoured to produce excellent timber.
The tallest known specimen of ‘James Gordon’ grew at the Villa Zorze Rossetti in the kindly climate of Piedmont in north-eastern Italy, and was a remarkable 42.5 m tall when it blew down in 2008 (monumentaltrees.com 2023); it had been planted around 1790. A few Spanish specimens of ‘James Gordon’, such as the much-photographed example in the Madrid Botanical Garden, may be almost as old.
Zelkova carpinifolia seems to have been introduced to North America by William Hamilton, who collected trees in England in the 1780s and grew them on his estate in Philadelphia, which after his death become the city’s Woodlands Cemetery. Hamilton planted a zelkova avenue, but the local conditions (American Climate Zone 7) seem not have suited the tree as well as does the climate of western Europe. By the start of the twentieth century a few low, bushy trees of ‘Z. crenata’ remained (Elwes & Henry 1906–1913), although the last of these died before 1921 (Philadelphia Historic Plants Consortium 2012). Z. carpinifolia is currently represented in the Cemetery by a fine specimen of ‘James Gordon’ which is said to have been raised as a sucker from Hamilton’s trees, and no longer shows signs of stress in the local microclimate (Philadelphia Historic Plants Consortium 2012; monumentaltrees.com 2023).
All of the oldest surviving zelkovas in western Europe, which as indicated above seem likely to have originated from James Gordon’s nursery, grow on their own roots. This fact may have contributed to the general idea that they were seedlings and represented the typical, wild shape of Z. carpinifolia, but this a fairly easy tree to raise vegetatively from cuttings and root suckers. (In the author’s experience, the sucker does need to be dug up with a larger length of root attached to it than is true, for example, for the Stagshorn Sumach Rhus typhina.) One question which cannot be answered with any confidence is whether Gordon originally obtained seed, and was fortunate enough to find one vigorous fastigiate seedling which was the plant he chose to propagate, or whether he imported living material which had already been selected further east for its strong upright growth. Contemporaneous examples of clones introduced to England vegetatively and quickly and widely distributed include the Lombardy Poplar and the English Elm Ulmus minor ‘Atinia’. Z. carpinifolia is known to have been introduced to the Jardin des Plantes in Paris in 1786 as a four-year-old sucker (Michaux 1831), although this plant has long gone and one at least of the Garden’s current examples is a spreading tree of rather youthful appearance, with unusually weeping outer branches (monumentaltrees.com 2023). A huge ‘James Gordon’ at Tortworth Court, Gloucestershire, England, was raised as recently as 1903 as a sucker from the Wardour Castle population (Elwes & Henry 1906–1913).
Loudon reports that by the 1830s the traditional method of reproducing Z. carpinifolia had become to graft it on English Elm (Loudon 1838). No old grafted trees seem to survive; this can readily be explained by the hypothesis that such grafts were less robust, and also by the particular susceptibility of the rootstock to Elm Disease. As late as 1985, Z. carpinifolia was sourced from Hilliers nurseries for the Bishop of Winchester’s arboretum at Wolvesley in Hampshire as a graft at the base on some unidentifiable elm, and has grown bushily (Tree Register 2023). It seems quite unlikely that any zelkovas were successfully raised from seed within western Europe during the earlier stages of the species’ establishment in cultivation; Loudon observed that in France at this time, the drupes always dropped before the seed was ripe (Loudon 1838).
Like the Caucasian Wingnut Pterocarya fraxinifolia and the Persian Ironwood Parrotia persica from the same forest communities, Z. carpinifolia can sucker very profusely. It is more manageable in this respect than the wingnut, and the suckers usually only arise in abundance after acute stress or the loss of the parent plant. Beauport Park near Hastings was one of England’s foremost arboreta through the nineteenth century but large parts of the estate have hardly received any management since then, and now provide a fascinating laboratory in which to study the long-term behaviour of naturalised exotic trees. A large specimen of ‘James Gordon’ here blew down in 1987; 35 years on, the dead branch structure remains largely intact, as a testament to the durability of zelkova timber, whilst a grove of fastigiate suckers about 30 m wide has successfully outcompeted the native seedling trees which have otherwise colonised this corner of the estate; ‘James Gordon’ clearly has the capacity to persist in our climate for a very long time. (Because they have grown up in close competition, these suckers, which were up to 17 m tall by 2023, lack the massed forks of single older specimens.) In south-western France, at least two standing examples of ‘James Gordon’ lurk within thickets of maturing fastigiate suckers (monumentaltrees.com 2023). At Tortworth Court in England, the suckering habit of ‘James Gordon’ has been successfully exploited to create a neat hedge around the parent specimen, on ground too dry and shaded for much else to flourish.
The genetic study of Christe et al. (2014) shows that ‘James Gordon’ represents part of the eastern (and largely Iranian) population of Zelkova carpinifolia. This is, in fact, to be expected: although the western, Caucasian and Anatolian population lies geographically closer to England, these mountains were effectively terra incognita to western Europeans until later in the eighteenth century, while the Iranian forests lie quite close to the main route of the Silk Road westwards through Tehran to Istanbul. One other outstanding tree from these same Iranian forests, the less hardy Albizia julibrissin, had already made this journey, and was introduced to Italy from Istanbul by Filippo degli Albizzi in the 1740s (Wellcome Collection 2023).
The first western botanist to have the opportunity to study Zelkova carpinifolia in its native forests seems to have been Peter Pallas, whose explorations on behalf of the Russian government had taken him as far as the Caspian Sea in 1768–74; in 1789 he described the species under the name ‘Rhamnus carpinifolia’ (Royal Botanic Gardens, Kew 2023). A decade later, André Michaux also observed zelkovas in Iran during an expedition of 1782–5. Confusedly, Michaux is often credited with the first introduction to the west, but the failure of his son François André in his monograph on the species (Michaux 1831) to say that the elder Michaux did make an introduction in the 1780s seems tantamount to a conclusive statement that he did not do so. The elder Michaux may however have been the first person to associate the saplings that were probably familiar to him around Paris with their wild ancestors. Seed of Z. carpinifolia collected in the Imereti region of Georgia (and therefore representing the species’ western haplotypes) was sent to France in 1831 by Jean-François Gamba (Elwes & Henry 1906–1913); the absence of any photographic evidence for surviving trees of this vintage in western Europe which are not ‘James Gordon’ could be taken as evidence that this introduction was unsuccessful, but as a caveat it also needs to be observed that the photogenic qualities of ‘James Gordon’ make it likely that any evidence for other less striking survivors is liable to be swamped out.
The photographic record in monumentaltrees.com 2023 suggests a considerable population of old Zelkova carpinifolia in the UK, Ireland, France, the Netherlands, Italy and Spain, all of which are ‘James Gordon’, and smaller numbers of much younger specimens further east in Europe, none of which represent the form. The ubiquity of this magnificent clone among eighteenth- and nineteenth-century plantings might be characterised as a horticultural triumph, but as something of a missed opportunity for the ex situ cultivation of a species which is increasingly scarce in the wild. The genetic study by of Christe et al. (2014) – which admittedly focused on botanic gardens rather than widespread ornamental plantings – did in fact indicate that a wide range of genotypes are already in ex situ cultivation. However, only two of the specimens studied by Christe et al. were of known wild origin.
In the UK at least, the oldest surviving Z. carpinifolia which does not seem to represent the clone ‘James Gordon’ forms part of an arboretum planted in 1935 as an extension of Alexandra Park, a public park in Hastings, East Sussex (Tree Register 2023). The source of these trees – which also include the first known public planting of Fagus sylvatica ‘Dawyck’ – is not known, but is very likely to have been the Hillier nurseries. The zelkova, growing on its own roots, had a sprawling, multistemmed and frankly unprepossessing habit and was only about 18 m tall when it blew down in 2014 (Tree Register 2023). Parts of the collapsed crown have continued to resprout, while a thicket of crooked suckers has grown up from the roots. (Informatively perhaps, this specimen was featured in the 1988 Supplement to Trees and Shrubs Hardy in the British Isles (Clarke 1988) as Z. sinica, a species which had also been planted in this arboretum: for anyone familiar with the habit of ‘James Gordon’, ‘wild’ forms of Z. carpinifolia are liable to be misidentified, or simply overlooked.) A more vigorous spreading example of the species is 1979.15668 in the Bluebell Woods at the Royal Botanic Gardens, Kew, which was 20.5 m tall in 2022 and which from its growth rate was probably planted, from an unknown source, around 1950; perhaps of the same age, and well placed to show its widely domed habit, is 1973–11550, growing outside the Gardens on Kew Green in front of the Director’s House (Tree Register 2023). Whether any of these youngsters will ultimately attain the stature of the largest ‘James Gordon’ in cultivation seems moot: ‘James Gordon’ may well have been selected for its exceptional vigour as well as for its habit. Comparably gigantic trees up to 40 m tall are however reported from the wild population (Kozlowski & Gratzfeld 2013).
In the UK, a proportion of younger Z. carpinifolia plantings are slightly fastigiate, but less neatly so than older specimens of ‘James Gordon’. One possibility is that these trees have arisen in cultivation as hybrids of ‘James Gordon’ with other spreading seedlings; it might also be suggested that ‘James Gordon’, unlike most similar plants, becomes more rather than less fastigiate with age. It is probably not possible to distinguish ‘James Gordon’ by foliage features alone.
Plants of known wild origin which have recently become commercially available in the UK include seedlings from NJM 13.014 and NJM 13.016 (collected in Azerbaijan), and from PAB 13.047 (Royal Horticultural Society 2020).
Sadly, Zelkova carpinifolia is much less well known in North America than it is in western Europe. The indifferent performance of Hamilton’s original Philadelphia plantings may have contributed to this neglect, while the species’ role as a large-scale ornamental has been largely usurped in the New World by the east Asian Z. serrata, which thrives particularly well here; clones of this species have been selected for street planting which imitate, in diluted form, the habit of ‘James Gordon’. ‘James Gordon’ itself is represented by a fine example in the J.C. Raulston Arboretum in North Carolina (J.C. Raulston Arboretum 2023), among others, while the species – most probably in the form of ‘James Gordon’, propagated from the Woodlands Cemetery – was in Thomas Meehan’s Philadelphia nursery’s catalogue as early as 1880 (Philadelphia Historic Plants Consortium 2012). Younger American plantings include 1720/2007 at the New York Botanical Garden, which was wild-collected in the Georgian Caucasus (Royal Botanic Garden Edinburgh 2023).
As discussed in the entry for the species, a fastigiate clone of Zelkova carpinifolia can be traced back to James Gordon’s Mile End Nursery in east London in 1760; nearly all of the largest and oldest examples of the species in western Europe and the United States are known or can be assumed to have been propagated vegetatively from this stock. This variant is described here for the first time as a cultivar; this entry will be supported by a printed description in TSO Occasional Papers during 2023.
Along with the Lombardy Poplar (Populus nigra ‘Italica’), which had coincidentally reached England a year or so earlier (Aiton 1789) – and to exclude the Wheatley Elm Ulmus minor ‘Sarniensis’, which is sadly vulnerable to Dutch Elm Disease – Zelkova carpinifolia ‘James Gordon’ is perhaps the finest as well as the most vigorous erect-branched tree which we can grow. Above a variably short bole which is often deeply fluted – and hence shows off to maximum extent the species’ prettily flaking bark – a large number of main branches arise at steep angles and often fuse. (This inosculatory tendency, along with the species’ naturally durable timber, helps to make ‘James Gordon’ much more stable and longer lived than most trees with narrow and hence weak forks.) From this central scaffold, the minor branches arch out precisely to the horizontal, so that the species’ fine twiggery is much more graceful than that of most upright-growing trees. In summer, densely clad in the species’ small dark leaves, the crown is neatly egg-shaped; with its short bole at the base and billowingly serrated outline, this habit delightfully suggests the shape of each individual short-stalked oval leaf. In winter, the architecture of the major branches becomes visible, suggesting a giant urn on a pedestal or – as that bluff Yorkshireman W.J. Bean memorably if less flatteringly put it – ‘a monstrous besom’ (Bean 1981).
Although a tree whose ultimate spread can exceed 30 m is scarcely suitable for many of the spots which fastigiate trees are expected to fill, Z. carpinifolia ‘James Gordon’ offers perhaps the ultimate specimen for a large-scale and long-term formal feature. Its comparative scarcity can be attributed to the lack, until now, of a cultivar name and the failure of most garden writers to realise that Z. carpinifolia does not always grow like this: anyone hoping to cultivate ‘James Gordon’ and receiving instead a plant raised from seed is likely to be disappointed – although they will at least be assisting the cultivation of the larger part of the potential genetic diversity of this threatened species. In 2023, Van Den Berk Nurseries are perhaps the only supplier to advertise scions of ‘James Gordon’ separately from seed-grown Z. carpinifolia (van den Berk Nurseries 2023), though their sale name ‘Pyramidalis’ would only be valid if it had been published before 1959, for which no evidence has been found. (Meanwhile the Z. carpinifolia ‘Pyramidalis’ advertised and photographed by Cappellini Giardinieri in 2023 (Cappellini Giardinieri 2023) is something else, most probably Z. serrata ‘Musashino’.)
As the oldest specimens of ‘James Gordon’ steadily die from old age or blow down, this variant seems bound to become scarcer. However, it is an easy plant to reproduce, either from transplanted suckers or from cuttings. During the third quarter of the twentieth century at least one nursery was supplying ‘James Gordon’ top-grafted onto Zelkova serrata; examples of this rather bizarre (and unnecessary) creation survive in England at Danson Park in south-east London and at Brueton Park in the West Midlands (Tree Register 2023).