Carpinus betulus L.

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Credits

Owen Johnson (2022)

Recommended citation
Johnson, O. (2022), 'Carpinus betulus' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/carpinus/carpinus-betulus/). Accessed 2022-06-26.

Genus

Common Names

  • Common Hornbeam
  • European Hornbeam

Synonyms

  • Carpinus betulus subsp. carpinizza (Kil.) O. Schwarz
  • Carpinus carpinizza Kil.
  • Carpinus caucasica Grossh.

Glossary

cordate
Heart-shaped (i.e. with two equal lobes at the base).
dbh
Diameter (of trunk) at breast height. Breast height is defined as 4.5 feet (1.37 m) above the ground.
fluted
Channelled or grooved.
indigenous
Native to an area; not introduced.
introgression
Incorporation of genes from one species into the genotype of another through repeated hybridisation or repetitive backcrossing between a hybrid and one of its parents.
pollen
Small grains that contain the male reproductive cells. Produced in the anther.

Credits

Owen Johnson (2022)

Recommended citation
Johnson, O. (2022), 'Carpinus betulus' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/carpinus/carpinus-betulus/). Accessed 2022-06-26.

Tree to 30 m, often with many slender branches. Bark grey, smooth then with fine, predominantly vertical silver markings and shallow fissures; older branches and bole fluted. Shoots slender, grey-brown, zig-zag, with silky hairs at first; buds slender, brown, long-pointed, to 1 cm long, the tip usually incurved towards the shoot. Leaves ovate or slightly oblong, 4–10 × 2–5 cm, base rounded or slightly cordate, sometimes oblique, apex short-pointed; matt on both surfaces with silky hairs at first, which can persist under the veins; lateral veins rather parallel and rather impressed, in 10–13 pairs, each ending in a fine tooth between which are 2–5 secondary teeth, of smaller but irregular size; petiole 6–12 mm, with silky hairs at first. Male catkins c. 4 cm. Female catkins extending to 8 cm in fruit; bract 3-lobed, almost symmetrical, 2.5–4 cm long; middle lobe often toothed on both sides. (Bean 1976).

Distribution  AlbaniaArmeniaAustriaAzerbaijanBelarusBelgiumBosnia and HerzegovinaBulgariaCroatiaCzechiaDenmarkEstoniaFranceGeorgiaGermanyGreece In the north of the country HungaryIranItalyLatviaLiechtensteinLithuaniaLuxembourgNorth MacedoniaMoldovaMontenegroNetherlandsPolandRomaniaRussia European Russia and the Caucasus SerbiaSlovakiaSloveniaSpain In and near the Pyrenees Sweden In the far south of the country SwitzerlandTurkey Near the Black Sea UkraineUnited Kingdom Native to south-east England; widely naturalised further north

Habitat Woodlands on heavy base-rich soils.

USDA Hardiness Zone 4-5

RHS Hardiness Rating H6

Awards AGM

Conservation status Least concern (LC)

On the right soils within its native range European Hornbeam can be an abundant tree, sometimes growing in pure stands and quickly colonising ungrazed grassland; it has no significant pests or diseases and can be very long-lived. Partly because it has evolved to exploit ‘difficult’ soils such as heavy clay, Hornbeam is not one of Europe’s tallest growing trees, but it can spread widely and carries heavy masses of foliage, somewhat limiting the type’s usefulness in gardens and formal plantings. In general appearance it is most similar to the European Beech (Fagus sylvatica) and is frequently confused with it, but even in winter, without its characteristic, pleated leaves and hanging earings of green seed, its grey bark is distinctive, vertically marked with silver snakings and fluted as if muscles are bunched under its surface. (One American name for the hornbeams is ‘musclewood’.) European Hornbeam and Beech specialise in diametrically opposed conditions, with the roots of the hornbeam allowing it to grow in seasonally waterlogged conditions but not on the lightest, sandy soils. Like beeches, hornbeams hang on to their dead brown leaves through winter in the sapling stage, and this character can be maintained by clipping. This makes both trees particularly useful for hedging and topiary; Beech’s glossy leaves and perhaps the more attractive, but Hornbeam will thrive in heavier and more challenging soils. The main loss in a Hornbeam hedge or topiary is that of the yellow autumn colour which is the brightest thing about the mature tree.

Even in the United States, where another species (Carpinus caroliniana) is native, European Hornbeam is planted for preference in urban situations as it has a reputation for being more adaptable and pollution tolerant (Koller & Dirr 1979), though it is not quite so hardy; in ‘Fastigiata’ it has also produced the best-shaped sport for tighter situations.

Hornbeam timber is exceptionally heavy and dense – its name translates into modern English as ‘hard tree’ – rather like that of European Yew (Taxus baccata). This structural toughness allows the tree to grow particularly slender branches, and, in marked contrast to beeches, hornbeams can continue to survive long after fungi have started to hollow out the trunk. Hornbeam has long been an important fuel wood, burning slowly at high temperatures and making excellent charcoal; in various parts of its range trees were coppiced or pollarded to provide a continuous supply of manageably sized logs. The timber has only ever been of value on a local scale, but is hard, difficult to work, and its usefulness is restricted to indoor use only; it was at one time used in piano manufacture (Elwes & Henry 1906–1913). As pollards, Hornbeam can reach huge sizes; the largest known grew at Easton Park in Essex and had a trunk or bolling 3 m wide when it finally burnt down in 1956 – this was one of the trees which inspired the estate’s owner, the Hon. Maynard Greville, to become one of England’s first chroniclers of notable trees (Tree Register 2022). The largest Hornbeam known today, another pollard relic in Ware Park, Hertfordshire, had a dbh of 2.18 m in 2002 (Tree Register 2022).

The gnarled and fluted trunk of an ancient Hornbeam can strongly resemble a big yew’s (except in colour) and it is easy to imagine that such trees are almost as old. Extensive research has been undertaken into the probable ages of western Europe’s biggest yews, many of which are about the size the Easton Hornbeam was prior to its demise. For our biggest hornbeams, by contrast, which tend to grow in out-of-the way corners of the countryside rather than churchyards etc., very few historical measurements are available to help us to judge how slowly they are adding girth and hence how old they are likely to be. An apparent pollard, now preserved in the Woodland Glade at the Royal Botanic Gardens, Kew, has added about 35% to its girth in the 110 years since it was first measured, but could well have grown slower in its youth when it was actively managed. This rate is similar to that of an open-grown tree at Murthly Castle, Perthshire, which added just over 30% in the period 1906 to 2017. One of the largest of many ancient pollards in Bockhanger Wood, a private woodland near Ashford, Kent, seems likely from its burred top-heavy shape to be the same one that was described and measured by Henry Elwes in 1908; over the same span of time as the Kew tree this has only added 6% to its girth. It would therefore be perfectly reasonable to assume that this tree is over a thousand years old and that hornbeams could genuinely rival yews as northern Europe’s oldest trees, but to raise such speculations on such limited evidence is perhaps unhelpful.

In better soils and with a full canopy to power their growth, planted hornbeams can certainly grow faster than this and are likely to decline and die at a less advanced age. The sudden demise in 2020–21 of one of England’s most impressive wild hornbeams at Brede in East Sussex, a former hedgerow pleacher with a fused mass of stems 3 m wide (on the long axis), was however very unusual (Tree Register 2022).

The tallest accurately measured hornbeams – at Kasteel Gaasbeek in Belgium and in the Białowieża Forest in Poland – are a little over 34 m tall (monumentaltrees.com 2022). In combination these statistics suggest that Carpinus betulus is significantly the largest-growing member of its genus.

Hornbeams need a modicum of summer warmth to ripen their fruit and the north-western limit of the natural range is generally supposed to be the English Midlands, but they grow very well in cooler conditions and have been widely planted for so long that it is hard to be certain. At Dunganstown Castle in Co. Wicklow, Ireland, an ancient Hornbeam with a dbh of 1.84 m in 2010 is likely to be Ireland’s oldest planted – or at least exotic – tree (Tree Register 2022). Some very old Hornbeam in wooded parts of the Scottish Highlands such as Glen Lyon give every impression of growing ‘wild’, while a remarkable, open-grown tree in the grounds of Murthly Castle near Dunkeld is so deeply fissured, hollowed and haggard it is tempting to imagine it is a lone survivor from ancient Birnam Wood, but in truth it is unlikely to have known Macbeth. Measured in 1906 when it was c. 20 m × 95 cm dbh (Elwes & Henry 1906–1913), by 2017 the Murthly Hornbeam remained a stubborn 20 m while its trunk had increased to 1.24 m dbh (Tree Register 2022).

In the south and east of its range, Carpinus betulus grows alongside C. orientalis, a smaller plant with daintier foliage and unlobed fruit-bracts. In the Caucasus, the two species are assumed to have hybridised to give rise to C. × schuschaensis, and it is also possible that some degree of introgression has contributed to the distinct appearance of some C. betulus in southern and eastern Europe. Two such forms have been described in the past as separate species. C. carpinizza Kil., from the Carpathian Mountains and surrounding regions, with a cordate leaf base and only seven to nine pairs of lateral veins; planted in Westonbirt National Arboretum in Gloucestershire in 1929, a tree of this origin has erect branches from wide-spreading low limbs and a bark more rugged – even scaly – than native examples. Two 1937 accessions in the hornbeam collection at Kew, from LNSY 1482, are similar in overall appearance (Tree Register 2022). C. caucasica Grossh., from the Caucasus east to Iran, was first described in 1940 with pollen grains half the normal size of C. betulus (Clarke 1988). Plants grow under this name in several UK collections and have been introduced by John Whitehead (Whitehead 21 at Kew) and from Azerbaijan (a 1986 accession at the Sir Harold Hillier Gardens). At Kew an older tree from Georgia was planted in 1967 (Tree Register 2022; Rushforth 1985) while early in the 21st century, C. caucasica was commercially available from Ian FitzRoy in Kent (Royal Horticultural Society 2006). Such trees grow and look very much like indigenous forms of C. betulus, and Plants of the World Online (Plants of the World Online 2022), whose nomenclature is followed in this account, relegates both C. carpinizza and C. caucasica to synonomy with C. betulus.

Just as in Ulmus, 19th century nurserymen in Germany and the UK seem to have delighted in selecting and marketing minutely different sports of the native hornbeam. In the case of the elms, these clones now stand on the brink of extinction and considerable effort is put into re-identifying and preserving them. But Carpinus is not a threatened genus, and oblivion may be judged the best place for many of the named forms. The list of cultivars below excludes some of these, and lumps others in representative groups.


'City-shader'

A rare example of a clone selected for its general shapeliness in an urban situation, not for erect branching; available in Germany and the Netherlands (Michielsen 2009).


'Columnaris'

Synonyms / alternative names
Carpinus betulus f. columnaris (Beissn.) Späth

Wild hornbeams often grow with many slender, almost vertical central branches and several selections have been made from such trees: these are the genus’ nearest approximations to a fastigiate tree. ‘Columnaris’ was sold by Späth of Berlin from 1891 (Bean 1976) but its name – suggesting a tree proportioned like a column – is quite inappropriate to the few mature examples grown as the form today, which are rather bun-shaped, with steep, neat limbs and no central axis (and hence lower and wider than the familiar clone ‘Fastigiata’). The leaves are unusually broad and rather oblong, and are carried in attractively dense masses. Since Bean described the clone as ‘spire-like when young’ and ‘always with a central leader’ (Bean 1976), it seems probable that more than one mutation has been sold under this name.

See also ‘Pyramidalis Nana’ and ‘Globosa’.


'Columnaris Nana'

The oldest known examples of this clone, which combines a compact semi-dwarf habit with the fastigiate branching of ‘Columnaris’ (and ‘Fastigiata’), grow in the Valley Gardens at Windsor Great Park and were 7.5 m and 6 m tall in 2021 (Tree Register 2022). Their origin is not known, but to be a valid name the clone must have been available since at least the 1950s. Another example was planted at the Dawes Arboretum in Ohio in 1996, and the clone was sold by Mallet Court Nursery in Somerset from 2002 (Hatch 2021–2022). The Windsor trees remain very dense and keep a pointed tip; the individual branches create slight billows within the overall shape of the canopy.

Several very similar clones have been selected, listed below. See also ‘Globosa’.

  • ‘Brownstone’ Selected at the University of Georgia, USA, by Will Corley (Dirr 2009).
  • ‘Cornerstone’ Selected at the University of Georgia, USA, by Will Corley (Dirr 2009). Darker foliage than ‘Brownstone’ and with excellent tolerance of summer heat (Hatch 2021-2022).
  • ‘Compacta’ Plants have been grown at the Arnold Arboretum under this name since 1912, and were made commercially available in 1942 (Wyman 1948).
  • ‘Monument’ (‘Fastigiata Monument’) Of Italian origin and may be the same plant as ‘Columnaris Nana’ (Dirr 2009). It is currently available from several UK sources (Royal Horticultural Society 2020).
  • ‘Yewdell’ Grown at the Dawes Arboretum and presumably originating at Yew Dell Botanical Gardens in Kentucky, where it is no longer grown. This may also represent a renaming of ‘Columnaris Nana’ (Hatch 2021-2022).

'Fastigiata'

Common Names
Ace of Spades Hornbeam
Fastigiate Hornbeam

Synonyms / alternative names
Carpinus betulus 'Pyramidalis'
Carpinus betulus f. pyramidalis Dippel
Carpinus betulus f. fastigiata (G. Nicholson) Schelle

Awards
AGM

Though it has been sold since the 1880s under more than one name (Bean 1976; Hatch 2021–2022), the plant grown today as ‘Fastigiata’ seems to represent a single clone and remains by far the most popular selection of any hornbeam. It is not exactly fastigiate – saplings soon spread outwards and older trees can be broader than tall – but the many slender closely ascending branches create a striking architecture and until it is mature the crown maintains a conic or narrowly-rounded apex, rather like the outline of the spade in a deck of cards. Some pruning is necessary to create a couple of metres of clean trunk and to suit the tree for street use. The crown’s many, close weak forks may look like a recipe for disaster, particularly in summer when each branch is laden with its dense masses of neat foliage, but the inherent strength of hornbeam wood means that this is really one of the most reliable and low-maintenance of urban trees, and one which is as likely as any to continue to look just like its twins within a formal planting. ‘Fastigiata’ is potentially long-lived: of the pair planted in the hornbeam collection at Kew in 1894 – one from Croux and the other from Hesse (Bean 1976) – one remains in fine shape, while the other was experimentally pollarded in 2021–2 (Tree Register 2022). Although growth is a little slower than the type, another planted by Sir Henry Elwes at Colesbourne in Gloucestershire in 1902, and sheltered by other trees on a good soil, has reached 26 m (Tree Register 2022).


'Fastigiata Cucullata'

Synonyms / alternative names
Carpinus betulus f. cucullata hort. ex H.J.P. Winkl.

A hornbeam combining an upright habit with hooded leaves was described from the Muskau Arboretum in 1864 as ‘Carpinus betulus fastigiata cucullata’ (Petzold & Kirchner 1864). It appears lost to cultivation.


'Fielder's Tabular'

A similar clone to ‘Horizontalis’, perhaps selected by Fielders Farm Nursery in Kent, UK. An example planted in 1988 at the Sir Harold Hillier Gardens was 8.6 m tall by 2017 (Tree Register 2022). It has not made a striking tree.


'Foliis Argenteovariegatis Pendula'

This remarkably-named plant is distinguished from other variegated forms (see ‘Variegata’) here on account of its habit: This sport combines white-mottled leaves with a marginally weeping habit and was selected before 1905 in Podzamcze, Poland, by Feliks Rożański. Almost a century later a surviving plant was found by Włodzimierz Seneta and distributed by the Szmit Nursery (Szmit nursery 2022). This clone is now available from several UK nurseries (Royal Horticultural Society 2020).


'Frans Fontaine'

‘Frans Fontaine’ is the most familiar (in Europe) of various clones which it was hoped would improve on the stalwart ‘Fastigiata’, at least in terms of remaining more slender. The original plant was a street tree in Eindhoven in the Netherlands (Edwards & Marshall 2019) named around 1983 after a leading Dutch dendrologist and landscape architect (Van Den Berk UK Limited 2022; Nauta 2022). Ironically, Fontaine’s French surname means ‘fountain’ in English, creating a false expectation in some countries that this is a weeping tree.

‘Frans Fontaine’ has darker leaves than ‘Fastigiata’; although slenderer in youth it is less tidy, and seems likely to become equally spreading with maturity. Remarkably, it is claimed to produce only male catkins, meaning that its fruit will not litter pavements in autumn (Van Den Berk UK Limited 2022).

Several very similar selections have recently been made:

  • ‘Albert Beeckman’ (‘A. Beeckman’; ‘Beeckman’) This clone may have a better central axis (van den Berk Nurseries 2022). An example was planted at the Sir Harold Hillier Gardens in 2011 (Tree Register 2022).
  • ‘Dams’ Also added to the Sir Harold Hillier Gardens in 2011 (Tree Register 2022) this may have arisen in Austria (Prascak Nursery Catalogue 2022).
  • ‘Gerry Chaster’ Vase-shaped and even as a sapling it sheds all its leaves in autumn (Michielsen 2009).
  • ‘JFS-KW1CB’ (EMERALD AVENUE®) Selected in Oregon for its good central axis and heat tolerance (J. F. Schmidt Nursery Catalogue 2022).
  • ‘Lucas’ With a larger and darker leaf than ‘Frans Fontaine’, it tends to retain its dead foliage through winter (Edwards & Marshall 2019; van den Berk Nurseries 2022).
  • ‘Nord’ An Italian selection (Michielsen 2009).
  • ‘Pinocchio’ Selected in Missouri; it is vigorous and quite narrow but untidy (Hatch 2021-2022). A 2006 accession at the Sir Harold Hillier Gardens was already 10 m tall by 2018 (Tree Register 2022).
  • ‘Stegemann’s Primus’ (‘Stegemanns’) Selected in Germany by J. Stegemann in 2005, this is a vigorous tree with dark green, very corrugated leaves which flush with a bronze tint (Pépinières Minier 2022; Provender Nurseries 2020).
  • ‘Streetwise’ Selected in the 1980s by the Hilliers Nurseries; autumn colours include both yellow and orange (Dirr 2009).

'Globosa'

Synonyms / alternative names
Carpinus betulus 'Globosa Nana'
Carpinus betulus 'Globus'

‘Globosa’ differs only questionably from ‘Columnaris Nana’ (q.v.) as a slow and compact hornbeam with dense upright branching and a pointed tip into maturity. The dense foliage tipping each branch creates a cumulus effect (Hatch 2021–2022). In 1999 it was grown in the Savill Garden at Windsor Great Park as ‘Globosa Nana’ (Dirr 2009), while the ‘Globus’ current offered by Bluebell Nursery in the UK (Bluebell Arboretum and Nursery 2022) appears to be the same thing.


'Horizontalis'

Synonyms / alternative names
Carpinus betulus f. horizontalis Simon-Louis

A sport with level branches found by Emile Jouin near Metz around 1900, and distributed by Simon-Louis Frères (Bean 1976; Hatch 2021–2022). The example at Kew, accessioned in 1903, has grown in a normal shape to 20 m, and a scion planted in 2014 has developed a rather upright habit from the start (Tree Register 2022). ‘Horizontalis’ was available Mallet Court Nursery early in the 21st century (Royal Horticultural Society 2006). Low, flat-topped trees can often be seen in woodland but the habit in this case is probably a response to dense shading.

See also ‘Fielder’s Tabular’ and ‘Rogów’.


'Incisa'

Common Names
Cut-leaved Hornbeam
Cut-leaf Hornbeam

‘Incisa’ has become the commonest name under which hornbeams are grown whose leaf margin’s double-toothing is sufficiently exaggerated to count as lobing. This is one of the oldest selected variants of the species and was described at Kew in 1789 by William Aiton (Bean 1976); similar sports can sometimes also be found growing wild (including a five-metre seedling in the author’s local public park, Alexandra Park in Hastings). Historically, trees of this sort have been sold under various names (see below).

In the UK, cut-leaved hornbeams are not rare as planted trees, but the lobing does not create a visually very distinct tree – as it so memorably does in the case of the Fern-leaved Beech, Fagus sylvatica ‘Aspleniifolia’. Today’s population seems to include several different clones, though it is hard to match these to the variety of historically available names. Older examples often have a spreading, rather crooked habit and can become big: one in Quarry Park in Shrewsbury, with rather shallow lobes, had a trunk 104 cm thick in 2004 (Tree Register 2022). A tree of similar proportions at Tyntesfield in Somerset is taller and straighter, and has much reversion, while one in the Yorkshire Museum Gardens in York is particularly low and twisted (Tree Register 2022). Two shapely old trees in the Corner Cap field at Hergest Croft in Herefordshire have more rounded lobes (Tree Register 2022). A clone which was quite widely planted in the UK through the middle years of the 20th century has quite deep but irregular lobes and develops a strikingly neat, semi-fastigiate habit, and cannot be matched with confidence to anything in the historical literature.

The Tree Register’s historic records include a ‘Quercifolia Aureus’ 13 m tall at the National Botanic Gardens, Glasnevin, Dublin in 1993, suggesting a tree with cut, yellow leaves. A cut-leaved variegated hornbeam was described by Steven Falk from Brueton Park in Solihull in 2007 (Tree Register 2022) but has not be relocated. ‘Westonbirt’ is an apparently similar selection (Michielsen 2009), but no longer seems to grow at the Westonbirt National Arboretum and may be lost.

  • ‘Asplenifolia’ With particularly regular lobes and slightly larger leaves than typical (Bean 1976).
  • ‘Incisa’ (f. incisa (Aiton) C.K. Schneid.) With short leaves with only about six pairs of side-veins and coarse, irregular lobing (Bean 1976).
  • ‘Heterophylla’ With some leaves of normal shape (but these cut-leaved sports tend to revert readily). Younger trees are still grown under this name at the Sir Harold Hillier Gardens (Tree Register 2022) and at the Dawes Arboretum in Ohio (Dawes Arboretum 2022).
  • ‘Minoor1’ (MINOR GLOBEPBR) A cut-leaved hornbeam of compact habit, sold from 2020 (van Vliet New Plants 2021). It is offered as a globular, top-grafted bush but produces strong shoots and will need regular pruning to maintain this shape.
  • ‘Quercifolia’ (f. quercifolia (Desf.) C. K. Schneid.) With lobing described as ‘oak-like’, and a tree grown under this name at the Beale Arboretum in north London has more rounded lobing than in most cut-leaved variants (pers. obs.).
  • ‘Pruhonice’ From Pruhonice Park in Czechia, it may now only be known from a black-and-white print which suggested that it may also have been variegated (Michielsen 2009).

'Lochglow'

Synonyms / alternative names
Carpinus betulus ROCKHAMPTON REDPBR

A sport with reddish orange autumn colour, selected by Geoff and Pattie Locke at Mount Pleasant Trees, Gloucestershire, UK and now quite popular in British collections (Edwards & Marshall 2019). ‘Rockingham Red’, listed separately in 2020 by the RHS Plant Finder (Royal Horticultural Society 2020), appears to be a misprint.

Two other clones selected for autumn colour include:

  • ‘Bettembourg’ Originated by Tom Stein in Bettembourg, Luxembourg, in 2009. This is a very similar plant; its autumn colour can include pink (Michielsen 2009).
  • ORANGE RETZPBR Selected by Jean Blondeau in France in 2014 and available in the UK from 2020 (Provender Nurseries 2020); it is similar to ROCKHAMPTON RED but may be more upright and compact.

'Pendula'

Common Names
Weeping Hornbeam

Synonyms / alternative names
Carpinus betulus f. pendula (H. Massé) G. Kirchn.

Several sports with weeping branches have probably been selected and sold over the centuries, but all seem prone to revert, and some scions – like the tree planted as a centrepiece on the rock garden mound at Nymans in West Sussex – unfortunately refuse to weep from the start. The largest and oldest known example in the UK, in the Regency garden of Sezincote in Gloucestershire, has moderately weeping shoots and picturesquely contorted limbs, and could represent an original sport.

Other named, pendulous cultivars include:

  • ‘Pendula Dervaes’ Particularly low and very weeping examples are often assumed to be this clone, but it too can revert (reaching 17 m at the National Botanic Gardens, Glasnevin in Ireland in 2012 and 14 m at the Sir Harold Hillier Gardens in 2017 (Tree Register 2022)).
  • ‘Rovan’ Selected by Jef Van Meulder at Bokrijk in Belgium (Michielsen 2009).
  • ‘Vienna Weeping’ Propagated by Ed Scanlon in the United States in the 1950s from a weeping hornbeam planted by Emperor Franz Joseph in 1885 at the Hofburg Palace in Vienna (Dirr 2009); it likely represents a renaming of an older clone.

See also ‘Horizontalis’ and ‘Rogów.


'Purpurea'

Synonyms / alternative names
Carpinus betulus f. purpurea Dippel
Carpinus betulus 'Rubra'

‘Purpurea’ is not a purple leaved hornbeam: the leaves are supposed to have a slight reddish tint for a few days after they flush, after which it behaves just like a wild hornbeam. It was sold in the 1870s (Edwards & Marshall 2019) and one in the collection at Kew until 2010 was purchased from Dieck in 1889 (Tree Register 2022). Strangely, several commercial nurseries continue to offer this frankly pointless plant (Royal Horticultural Society 2020).


'Quercifolia Aureus'

A cultivar combining the deeply-lobed leaves of ‘Incisa’ with a yellow variegation; a tree survived under this name at the National Botanic Gardens, Glasnevin, Dublin, until at least 1993, when it was 13 m tall (Tree Register 2022). A 14 metre tree in the hornbeam collection at Kew, sourced from Smith of Worcester in 1873, was labelled simply as Carpinus betulus by 2022 but retained patches of cut foliage, patches of yellow-mottled foliage with green veins, and patches where the leaves are both incised and variegated. It is a less spectacular tree than this description might suggest, as the lobing is quite shallow and the yellow mottling can look pathogenic rather than genetic (Tree Register 2022).

A cut-leaved variegated hornbeam was also described by Steven Falk from Brueton Park in Solihull in 2007 (Tree Register 2022) but has not be relocated. ‘Westonbirt’ is an apparently similar selection (Michielsen 2009), but no longer seems to grow at the Westonbirt National Arboretum and may be lost.


'Rogów'

A semi-dwarf umbrella-shaped hornbeam, selected at Rogów Arboretum in Poland before 1994 (Dirr 2009).

‘Nicoerik’, selected by Jef Van Meulder at Bokrijk in Belgium, is similar (Michielsen 2009).

See also ‘Horizontalis’.


'Tortuosa'

A sport with contorted leaves, found at Pruhonice Park in the Czech Republic (Michielsen 2009).

‘Bernhard’s Ruffle’ (from Eike Jablonski, Luxembourg) is similar; the leaves may be monstrously crumpled, with crimped veins (Michielsen 2009).


'Variegata'

Common Names
Variegated Hornbeam

Synonyms / alternative names
Carpinus betulus f. variegata Dippel

A variegated hornbeam was in commerce by around 1770 and since then numerous clones have been described with leaves splashed or speckled in white, cream or yellow. None is overly showy and all seem prone to revert:

  • ‘Albomarmorata’ With white mottling.
  • ‘Albovariegata’ With finely white-speckled leaf (Hatch 2021-2022)
  • ‘Beskid Gold’ Appears to be an east European yellow-variegated clone (Michielsen 2009).
  • ‘Marmorata’ With white mottling, grown before 1867.
  • ‘Moonlight’ Raised by Eike Jablonski in Luxembourg prior to 2008, this has leaves quite boldly splashed in cream, at least as a young plant (Michielsen 2009).
  • ‘Punctata’ Leaves with whitish spots
  • ‘Ter Bronnen’ Selected by Kris Michielsen in Belgium in 2009, with leaves which are yellow near their margins (Michielsen 2009).
  • ‘Variegata Aurea’ (f. aureovariegata C. K. Schneid.) Yellow-variegated.
  • ‘Yellow Spot’ Sold in the United States in 2007, this has some yellow stripes or splashes.

(Dirr 2009; Edwards & Marshall 2019; Hatch 2021–2022; Michielsen 2009; Royal Horticultural Society 2020).

See also ‘Foliis Argenteovariegatis Pendula’.


'Waving'

A sport whose deeply impressed veins create a particularly corrugated effect to the jaggedly-toothed or lobulate leaves; briefly available in the United States from Hulsdonk around 2007 (Hatch 2021–2022; Michielsen 2009).