Liquidambar styraciflua L.

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Credits

Owen Johnson (2021)

Recommended citation
Johnson, O. (2021), 'Liquidambar styraciflua' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/liquidambar/liquidambar-styraciflua/). Accessed 2021-09-27.

Common Names

  • Sweetgum
  • Red Gum
  • Star-leaved Gum
  • Alligator Wood
  • Bilsted
  • Opossum Tree

Synonyms

  • Liquidambar macrophylla Ørsted
  • Liquidambar styraciflua var. mexicana Ørsted
  • Liquidambar tuberculata Silba

Glossary

clone
Organism arising via vegetative or asexual reproduction.
dbh
Diameter (of trunk) at breast height. Breast height is defined as 4.5 feet (1.37 m) above the ground.
taxon
(pl. taxa) Group of organisms sharing the same taxonomic rank (family genus species infraspecific variety).
variety
(var.) Taxonomic rank (varietas) grouping variants of a species with relatively minor differentiation in a few characters but occurring as recognisable populations. Often loosely used for rare minor variants more usefully ranked as forms.

Credits

Owen Johnson (2021)

Recommended citation
Johnson, O. (2021), 'Liquidambar styraciflua' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/liquidambar/liquidambar-styraciflua/). Accessed 2021-09-27.

Tree to 40 m, often with a long, straight bole. Bark greyish brown, soon ruggedly cracked into vertical ridges. Shoots glabrous, often developing corky wings from the second year. Buds mostly glabrous, conic, many-scaled. Stipules linear-lanceolate, 3–4 mm, shed to leave 2 scars adaxially near the base of the petiole, which is 4.5–15 cm long. Leaves 7–20 × 5–16 cm, with (3–)5(–7) lobes that are minutely serrated and rarely show large lobules at their shoulders, and are glabrescent but typically with small axillary tufts (but remaining densely pubescent beneath in arid parts of Mexico); lobes usually ovate-lanceolate. Male flowers in balls on downy spikes 3–6 cm long; female flowers in larger balls, c. 12 mm wide. Fruit globose, woody, 2.5–4 cm wide, with many sharp spikes and a roughened, folded surface between them. Fertile seeds apically winged, 8–10 mm. Flowering March–May. (Flora of North America 2021Bean 1981).

Distribution  Belize Cayo, in mountains El Salvador Chalatenango Department, in mountains Guatemala In mountains Honduras Altantida, Comayagua, Comaya, Cortes, El Paraiso, Lempira, Moraza, Ocoten, Olanch, Siguate Departments, in mountains Mexico Chipas, Hidalgo, Nuevo Leon, Oaxaca, Puebla, Tamaulipas, Veracruz; in mountains Nicaragua Jinotego, Madriz, Matagalpa, Nueva Segovia, Wiwili; in mountains United States Alabama, Arkansas, Connecticut, Delaware, Florida, Georgia, Illinois, Indiana, Kentucky, Louisiana, Maryland, Mississippi, Missouri, New Jersey, New York, North Carolina, Ohio, Oklahoma, Pennsylvania, South Carolina, Tennessee, Texas, Virginia, West Virginia

Habitat In fragmented montane forests through Mexico and Mesoamerica; in lowland and mountain woods, flood plains, swamps and riverbanks across the southeastern United States.

USDA Hardiness Zone 5

RHS Hardiness Rating H6

Conservation status Least concern (LC)

The sweet-gum is a common tree across the southern and eastern United States; in a country where so many species excel in autumn colour, it still gains special attention, in particular for the length of the show and the range of colours even single specimens can assume. In some individuals, the outermost leaves, which get the most sun, will deepen to purple, while the leaves further into the canopy turn crimson and orange, and those in deepest shade go lemon yellow; other trees will be uniformly scarlet or show a mix of reds and golds. The intricate star shape of each leaf seems to enhance the spectacle, almost as if you are looking into a deep-field image of the universe. The colour tends to start late, and, in the milder climate of Seattle, the autumn leaves of ornamental plantings can hang on the tree until the following March (Jacobsen 2006). This variability might suggest that Liquidambar styraciflua is a genetically diverse taxon; analysis by Hoey & Parks (1994) suggests that this is the case among the isolated populations in the mountain refugia of Mexico and Mesoamerica (where some of the trees are more or less evergreen), but that the United States seems to have been repopulated by one comparatively uniform group. (For a discussion of ‘L. tuberculata’ from Florida, see the introduction to Liquidambar here.) As a species with a relatively southern distribution, the Sweet-gum is not quite as cold-tolerant as many American trees, and only a few hardy selections will survive a severe winter in the Midwest or in southern Canada.

The leaves are aromatic when crushed and, in common with the genus’s other, hardier species, L. styraciflua exudes a scented resin from its inner bark if the trunk is damaged. Trees were tapped by the Cherokee, Choctaw, Houma, Koasati and Rappahannock tribes, and the gum was used medicinally and also chewed. As ‘American storax’, the resin is still used in some soaps and cosmetics, as a fixative in perfumes, glues and lacquers, and as a flavouring in tobacco (Flora of North America 2021). The species’s timber is used in cabinet making.

Its frequency and economic importance meant that L. styraciflua was among the first American trees to reach Britain. John Banister, the botanising chaplain of Virginia, sent one to his bishop, Henry Compton, in 1681 (Bean 1981). Its popularity was not instantaneous; there is remarkably little evidence to suggest that trees were particularly admired or noted for their autumn colour until the 20th century, but it is a long-lived plant, and today’s oldest cultivated trees, such as the champion at Syon in West London – 28.5 m × 103 cm dbh in 2017 (Tree Register 2021) – probably date from around the start of the 19th century, when Sweet-gums began to be more widely cultivated in Britain. In common with many broad-leaves from the eastern United States, the quite shiny leaves retain a brighter, fresher green through summer than any native of the United Kingdom. The habit is also attractive – almost spire-shaped in youth, then rather narrowly domed on a good straight bole, though in Europe this is often spoiled by early breakage due to the brittle wood, an event that can allow wood-rotting fungi to enter.

Another interesting feature – and an attraction for some – lies in the corky wings that tend to crust the young twigs from their second or third year. Two quite unrelated European trees, Field Maple (Acer campestre) and English Elm (Ulmus procera), grow similar flanges, but this is another of those fascinating botanical quirks for which no-one, as yet, seems to have come up with a plausible evolutionary explanation.

In recent decades Sweet-gum has been recognised as just about the best autumn-colouring tree in the cool summers and dank, uncertain autumns of northwest Europe where so many other American species disappoint; however, it does require at least moderate summer heat to thrive. It is now widely employed as a street tree and planted in quite small front gardens, and is available in a wide range of named selections. Summer sunshine and early frosts certainly help the autumn show; the species will survive in moderately alkaline soils – there is a big one at West Dean House among the South Downs of West Sussex (Tree Register 2021) – but, in these conditions, it will generally disappoint in autumn. Grown in a thin acid soil, conversely, it can suffer drought stress in a dry English summer.

European gardeners will probably be surprised to find that the Sweet-gum has recently become the United States’ ‘least favourite ornamental tree’ (Kerrigan 2014) and is now very little planted in its native regions. The problem lies in the sea-urchin-like fruit, which resemble novelty Christmas-tree baubles or – take your choice – a model of a virus particle and are surprisingly woody and long-lasting. It is only in recent warm summers that many trees in southern England have begun to flower at all freely, and the gum-balls remain an interesting novelty. In the hot conditions of most of the United States, trees fruit heavily each year, and the balls can twist an ankle, fly up from lawnmower blades, cut human flesh and generally prove impossible to rake up. In 2012 Springfield, Illinois, was the first American city to offer to remove Sweet-gums and to replant a substitute, at a discounted cost of $250 per tree; 338 specimens were quickly removed under this scheme. An alternative solution has been to drill holes round Sweet-gums’ trunks and to inject hormones to sterilise the tree. Kerrigan’s account in American Orchard (Kerrigan 2014) is well worth reading as a balanced insight into the species’s potential nuisance value and, in the light of ongoing climate change, it may sound a warning note for gardeners and local authorities in the warmer parts of Europe including, increasingly, southern England.

In its native habitat, the Sweet-gum is a big tree; boles well over 2 m thick have been reported in Mexico. One in South Carolina was recorded to be 60.5 m tall in 1944 (Jacobsen 2006), though recent records are all much smaller. In the United Kingdom and Ireland, growth is comparatively slow, and the tree struggles in the cool summers of the far north and west. There is a substantial but storm-damaged specimen at Montalto House in County Down, 15 m × 79 cm dbh in 2010, and one at Ellingham Tower in Northumberland was 13 m × 65 cm dbh in 2019, but the only vaguely respectable tree known in Scotland is one of 10 m × 53 cm dbh at Blairquhan in South Ayrshire in 2012. Some 200 km further north again, a plant at Innes House in Moray was a 6 m bush in 1991 (Tree Register 2021).

In southern Europe, growth matches that in the wild. A tree in the Piazza Santi Eusebio at Vercelli in northern Italy has a long bole 163 cm thick, while, in some gardens in the western Pyrenees, where trees from the eastern United States seem particularly at home, heights of 38 m have been recorded (monumentaltrees.com 2021).

L. styraciflua is one of few temperate trees that can be successfully cultivated in more tropical climates. It is a popular ornamental in Australia, though sometimes as an evergreen rather than an autumn-colouring tree. An example planted in 1904 at the Amani Botanical Garden in Tanzania was still there in 1979, in a tropical cloud-forest microclimate, and L. styraciflua is one of three Liquidambar species grown in the Johannesburg Botanical Gardens (Hsu & Andrews 2005). South Africa was also the origin of the clone ‘Paarl’, which is now planted around Europe.

Over the decades, many different clones of L. styraciflua have been selected. It should, however, be borne in mind that there may be no point in planting in England a cultivar named in Australia for its drought tolerance, or one selected in the American Midwest for its cold-hardiness and sparse seed production. Conversely, varieties celebrated for their autumn colour in northwest Europe may not obviously excel when planted where summers are longer and warmer. Some kind of local selection seems bound to take place anyway, as gardeners choose saplings grown from seed, in nursery rows in November, for their individual performance. As one of the delights of this display lies in its variety, it could be argued that it is actually advantageous to plant seedlings rather than uniform named clones, except perhaps within the formal constraints of an avenue. (One good avenue was planted – though not of a single clone – across the campus of Ashridge College, Hertfordshire, in 1937, on acid clay over chalk. The Savill Garden in Windsor Great Park has another, which was much damaged in the ‘Great Storm’ of 1987.)

A checklist of clones and variants that are not (yet) familiar enough or striking enough to warrant individual mention on this site, includes:

‘Autumn Glow’, with red to purple colour; selected probably by the Paul Goodwin nursery in the United States before 1976 (Hatch 2018–2020).

‘Briliqui’ (‘Pelluailles’), selected for its good form, autumn colour and limited seed production (Hatch 2018–2020).

‘Brotzman’ (‘Brodsman’, ‘Bratzman’), one of two clones selected for their hardiness in Madison, Ohio, around 1990 (Dirr 2009).

‘Byrne’, selected in California by the Saratoga Horticultural Foundation but perhaps lost to cultivation (Santamour & McArdle 1984).

‘Celeste’, offered by the Boskoop nurseries in the Netherlands in 2007 (Hatch 2018–2020).

‘China’, offered by the Boskoop nurseries in 2007 (Hatch 2018–2020).

‘Golden Drops’, sold in Australia in 2020 by (Yamina Rare Plants), without description, but perhaps a variegated clone.

‘Gotrev’, selected for its rich red autumn colour by the Boskoop nurseries in the Netherlands by 2007 (Hatch 2018–2020).

GRANDMASTER (‘Grazam’), with a good form and red and yellow autumn colour (Dirr 2009).

‘Hagen’, selected by the Hagen Nursery in California and planted at the Los Angeles State and County Arboretum in 1957 (Santamour & McArdle 1984).

‘Joseph’s Coat’, exhibited (in its ‘many colours’) by Lord Aberconway for the RHS in 1987 (Hsu & Andrews 2005).

‘Keith Davey’, selected by the Davey Tree Expert Company in Ohio in the 1980s (Hatch 2018–2020).

‘Kent’, sold by the Davey Tree Expert Company in the 1980s (Hatch 2018–2020).

‘Lynn’, sold in 2020 by Starborough Nursery in Kent and represented by a young tree in the Sir Harold Hillier Gardens (Royal Horticultural Society 2021, Tree Register 2021).

‘Nina’, represented by a young tree in the Sir Harold Hillier Gardens (Tree Register 2021).

‘Oktoberglut’ (‘October Glow’), sold by the Boskoop nurseries in the Netherlands in 2007 (Hatch 2018–2020).

‘Pieces of Eight’, known to Laurence Hatch by name only (Hatch 2018–2020); presumably golden at some time of the year.

‘Plattsburg’, a form with a good shape and remarkably rugged bark, found near Plattsburg, Missouri, and sold by Arborville Nursery, Holt, around 1993 (Hsu & Andrews 2005).

‘Quirky Disposition’, sold by Suncrest Gardens, Ohio (Hatch 2018–2020).

‘Red Spire’, the label on a young tree of good form at Lord Heseltine’s Thenford House Arboretum in Northamptonshire and perhaps selected here (Tree Register 2021).

‘Richared’, sold in 2001 by the Blue Mountain Nursery, Oregon (Hatch 2018–2020).

‘Roemer’, offered by the Boskoop nurseries in the Netherlands in 2010 (Hatch 2018–2020).

‘Soledad’, selected by the Saratoga Horticultural Foundation in California (Santamour & McArdle 1984).

f. suberosa, a name published by F Schwerin in 1933 for trees with particularly corky twigs (Santamour & McArdle 1984).

‘Sunnyvale’, found at Sunnyvale in California and selected by the Saratoga Horticultural Foundation (Santamour & McArdle 1984).

‘Wintergreen’, recently sold by the Boskoop nurseries in the Netherlands (Hatch 2018–2020). It is not evergreen.


'Andrew Hewson'

Synonyms
Liquidambar styraciflua 'Andrew Henson'

A vigorous selection with large, deeply lobed leaves that begin to turn deep reddish purple relatively early in autumn. In the Netherlands, it was sold from the 1990s (Hsu & Andrews 2005), and it is now available from several UK nurseries. The alternative name, ‘Andrew Henson’, is about equally frequent, and this issue cannot be resolved as no-one knows who Andrew was (Hsu & Andrews 2005).


'Anja'

A Dutch selection, sold by 1993, with a spreading habit and a long central lobe to its leaves, which begin to turn purple relatively early in autumn. The name commemorates Anja Zweinenberg of Boskoop (Hsu & Andrews 2005). It is now available in the United Kingdom.


'Anneke'

A sister tree to ‘Anja’, named after Anneke Zweinenberg of Boskoop and sold in the Netherlands by 1993 (Hsu & Andrews 2005). Selected for its rich autumn colour, it is now available in the United Kingdom.


'Aurea'

A ‘Golden’ Liquidambar may first have been offered for sale by Henry Kohankie and Son in Ohio in 1940, under the (valid) name ‘Aurea’ (Santamour & McArdle 1984). At the Arboretum Adeline in France, a form with leaves yellow in spring, fading to green then turning pinkish in autumn, was still grown under this name in 2005 (Hsu & Andrews 2005). Confusion arose, however, in 1962, when Ed Scanlon, also in Ohio, marketed what is believed to have been the old Dutch clone ‘Variegata’ under the (invalid) name ‘Aureum’, leading many commentators to assume that ‘Aurea’ is just a synonym for ‘Variegata’ (Hsu & Andrews 2005).

Since that time, a range of golden-leaved Sweet-gums have been marketed, many of them probably representing the same mutation. ‘Aurora’, first sold by Alphons van der Bom in the Netherlands in 1977, was described as a compactly upright tree with bright, mottled yellow leaves. However, the clone sold in the United Kingdom is green-leaved, at least if the example at the RHS Wisley garden in 2005 had not reverted (Hsu & Andrews 2005). Jacobsen (2006) and Dirr (2009) also describe the trees sold in the United States as green-leaved, with Dirr commenting on their poor autumn colour. A photograph from Poland, meanwhile, appears to show the clone ‘Variegata’.

‘Aurea Compacta’ (an illegitimate name) was sold by J. Clarke in California from 1966 as a compact and gold-leaved form, but seems lost to cultivation (Hatch 2018–2020).

‘Goldmember’, represented by a yellow-leaved plant in the Winter Garden at the Sir Harold Hillier Gardens in Hampshire, has been sold in Europe from around 2006 (Hatch 2018–2020).

‘Matthew’s Gold’ was noticed as a street tree in Sydney, Australia, by Vic Ciccolella in 1980. Leaves of a good yellow were described as turning red in autumn, but the clone may be lost to cultivation (Hatch 2018–2020).

‘Schock’s Gold’, with bright yellow leaves fading to lime green, was admired by Larry Hatch as a young tree at the Juniper Level Botanic Garden in North Carolina in 2004 (Hatch 2018–2020) and has been available in the United Kingdom since 2006.

For other comparable but better-known selections, see ‘Gold Beacon’, ‘Golden Sun’, ‘Moonbeam’ and ‘Naree’.


'Black Parking'

This curiously named selection is now sold in Belgium by Les Jardins du Florilège, who describe (in English) a tree ‘with ovoid port, erect, glossy palmate leaves, green then yellow in autumn, with a beautiful green and yellow graphic’. The accompanying photograph, presumably taken in early autumn, shows a remarkable colour combination, with a central tongue of butter yellow on leaves that are otherwise a very dark Lincoln green, suggesting that this is a tree worth growing.


'Burgundy'

‘Burgundy’ has become perhaps the best known of the selections of Sweet-gum whose leaves turn a deep, purplish crimson in autumn. The colour is long-lasting and may persist until January in California (Santamour & McArdle 1984), and the first flush in spring is also purplish. The tree was selected by the Saratoga Horticultural Foundation in 1963 (Hatch 2018–2020). The tallest example at the Sir Harold Hillier Gardens in the United Kingdom had grown well to 13.5 m by 2018 (Tree Register 2021).

Other clones with similar autumn colour include ‘Burgundy Blush’, sold by Willoway Nurseries in the expectation of limited fruit production in the United States, ‘Dark Autumn’, sold by Larch Cottage Nurseries in Cumbria, ‘Summer Storm’, whose leaves in sun turn blackish from late summer (Hatch 2018–2020), ‘Black Beauty’, represented at John Ravenscroft’s Cherry Tree Arboretum in Shropshire (Tree Register 2021), and ‘Burgundy Spider’, sold by the Handy Nursery Company in Oregon and represented at the Dawes Arboretum in Ohio (Hatch 2018–2020).

See also ‘Thea’.


'Canberra Gem'

A tree selected for its suitability to the growing conditions of southeastern Australia. Its deeply cut leaves turn yellow and red in autumn (Yamina Rare Plants).


'Clydesform'

Synonyms
Liquidambar styraciflua EMERALD SENTINEL®

A fastigiate Sweet-gum, neatly conic as it grows older. It is not as narrow and striking as ‘Slender Silhouette’ (q.v.), but looks as if it may prove more robust in the long term. It has narrowly lobed leaves that turn yellow and orange in autumn. There is an example at the JC Raulston Arboretum in North Carolina (Hatch 2018–2020); it is now sold in the United Kingdom by Junkers Nursery.

Sweet-gums often take on a neat, conic habit in youth. One likely sport that is maintaining a remarkably neat habit, like that of the much-lamented Wheatley Elm (Ulmus minor ‘Sarniensis’), grows as a street tree in Acton in West London. The bent base shows it was planted as a large standard, which did not anchor itself before the stake failed, but, as a singleton, it seems unlikely to have been planted as a named fastigiate selection.


'Corky'

As its name suggests, the curious corky projections that are a feature of the young twigs of Liquidambar styraciflua are pronounced in this selection. They also tend to form many fine points, rather than continuous flanges, a character that Larry Hatch (Hatch 2018–2020) considers remarkably attractive. The oldest known example, at Longwood Gardens in Pennsylvania, was obtained from the Kingsville Nursery in Maryland in 1965, and there is another good example at the Boxerwood Woodland Garden in Virginia (Hatch 2018–2020). ‘Corky’ is now available from several nurseries in the United Kingdom.


'Festeri'

A form found by Mr Fester, a gardener at Kenmore Hospital, Goulburn, New South Wales, and named in his honour by the Hazelwood Brothers nusery in 1947 (Santamour & McArdle 1984). In the climate of eastern Australia, the red and orange autumn colour starts late and can last until midwinter. This old clone has recently surfaced in the United Kingdom, in the catalogue of the Endsleigh Gardens Nursery in Devon.


'Festival'

Synonyms
Liquidambar styraciflua 'Lee'

A potentially vigorous tree of narrow habit, with red and yellow autumn colour. It was selected by Paul Lee in California and sold from 1964 by the Saratoga Horticultural Foundation, originally under the name ‘Lee’ (Santamour & McArdle 1984). It is now offered by several UK nurseries, though both of the young trees in the collection at the Sir Harold Hillier Gardens in Hampshire have failed (Tree Register 2021).


'Frosty'

Synonyms
Liquidambar styraciflua 'Starlight'

‘Frosty’ was first found and sold by Tony Avent at the Plant Delights Nursery in North Carolina (Hsu & Andrews 2005); given summer heat, its younger leaves at least are finely speckled with white, providing an alternative to the similar but yellow variegation of ‘Variegata’. It was first sold in the United Kingdom in 2006. ‘Starlight’ probably represents the same sport (Dirr 2009).


'Gold Beacon'

Discovered in North Carolina before 2015, ‘Gold Beacon’ differs from the older clones of ‘Golden’ Liquidambar (see under ‘Aurea’) in its green new leaves that brighten to yellow through the summer. Autumn colours are described as red and orange (Hatch 2018–2020). The cultivar is already widely sold.


'Golden Sun' (PBR)

Another ‘Golden’ Liquidambar, first sold in 2002 (Hatch 2018–2020), ‘Golden Sun’ combines broadly lobed, yellow leaves with red young shoots and amber twigs, which photographs suggest can be very showy, especially if sited in a position with plenty of winter sunshine.


'Golden Treasure'

Synonyms
Liquidambar styraciflua 'Aurea Marginata'

Sweet-gums with a yellow marginal variegation have been in cultivation for many years, though perhaps not for long enough for the name ‘Aurea Marginata’ (or ‘Aureomarginata’) to have been a valid usage. These are slow-growing trees, whose variegation may fade to a creamy colour; it merges irregularly into the green centre of the leaf, and some leaves may be entirely yellow.

The clone ‘Golden Treasure’ was selected by Duncan and Davies in New Zealand before 1974 (Santamour & McArdle 1984) and was available in Oregon by 1979 (Jacobsen 2006). In autumn the leaves can turn a good burgundy red, with the margins turning white. The example at Wisley in the UK is slow and stunted (Hsu & Andrews 2005).


'Grant's Seedless'

A selection made by William and Elizabeth Grant in Illinois in 1983 (Hatch 2018–2020), combining hardiness, a vigorous erect habit, red and yellow autumn colour, with greatly reduced seed production.


'Gum Ball'

Synonyms
Liquidambar styraciflua 'Gumball'

This dwarf, mop-headed Sweet-gum was found by Hiram B. Stubblefield of Forest Nursery, Tennessee, around 1965 (Santamour & McArdle 1984). More recently, it has been quite widely planted, top-grafted on a leg of the type that is always liable to invade and overtake the crown, as is the case of the example at the RHS Garden Wisley (Tree Register 2021). Its name should not be confused with the species’s troublesome ‘gum-ball’ fruits, which this sport seldom produces, in fact (Dirr 2009). Autumn colour is (relatively) poor, and ‘Gum Ball’ is only likely to stand around –20°C of frost (Dirr 2009).

A few other named clones may represent the same mutation, or may be slightly more vigorous variants. ‘Globe’ may be better in autumn (Dirr 2009). ‘Lollipop’ is globose but perhaps not really dwarf (Dirr 2009). MilestoneTM, a recent release by Warren County Nursery (located, like Forest Nursery itself, in McMinnville, Tennessee) is described as semi-dwarf, and non-fruiting (Hatch 2018–2020). ‘Oconee’, found in Oconee County in Georgia (Hsu & Andrews 2005), may differ in its superior autumn colour – dark red to purple – but be more liable to fruit (Hatch 2018–2020). ‘Carnival’, available by 1990, is described as similar to ‘Oconee’ (Dirr 2009).


'Hapdell'

Synonyms
Liquidambar styraciflua HAPPIDAZE
Liquidambar styraciflua JubileeTM

A clone selected at the Bernheim Arboretum in Kentucky around 2000 (Hsu & Andrews 2005) for its dark red autumn colour and limited seed production. Its twigs become very corky from an early age. The form is now sold in the United Kingdom, sometimes under the erroneous name ‘Happy Days’.


'Jennifer Carol'

A compact clone (but not a dwarf, like ‘Gum Ball’, and also described as conic in habit) probably selected in Australia before 1985 (Hsu & Andrews 2005) and available in the United Kingdom since 2001 (Hatch 2018–2020). Narrow lobes give the leaves a particularly starry shape. The name sometimes appears as ‘Jennifer Carroll’.


'Kia'

A tree selected by R.W. Boden in Australia in 1968 for its narrow habit – ‘Kia’ is said to mean spear in an indigenous Australian language – and its orange and purple colours in autumn. It is available in the United Kingdom, but, in the Atlantic climate of Caerhays Castle in Cornwall at least, has made a very poorly formed tree.


'Kirsten'

Sold in the United Kingdom by Junkers Nursery since 2001, ‘Kirsten’ is recommended for its reliable autumn colours and small, narrowly lobed leaves (Hsu & Andrews 2005).


'Lane Roberts'

Awards
AGM

‘Lane Roberts’ has become one of the best-known autumn-colouring selections of Sweet-gum in the United Kingdom, its unusually large leaves turning dark red to purple, with those at the top of the crown going almost black. Sir Harold Hillier, visiting the Hertfordshire garden of Dr Cedric Lane-Roberts, was impressed by one of several seed-grown trees that Lane-Roberts had purchased from Hillier and obtained scion wood (Hsu & Andrews 2005). The clone was first listed by The Hillier Manual of Trees and Shrubs in 1971 (with an error for Lane-Roberts’s name that is probably too entrenched by now to be rectifiable). It has also been praised for its vigour and conic shape, against which should be set the very premature loss of Sir Harold’s first planting in the Sir Harold Hillier Gardens in 2005 (Tree Register 2008). The bark is less rugged than in most Sweet-gums.

Apparently even larger-leaved (Dirr 2009), the clone ‘Elstead Mill’ (presumably selected from the grounds of this restaurant in Surrey) was also available until 2015 in the United Kingdom (Royal Horticultural Society 2021). Its autumn colour was described as bright red.


'Levis'

A clone with yellow to red autumn colour, distributed by Marchants Nursery, Wimborne, Dorset, from 1955. The twigs lack the usual corky projections (Bean 1981). No surviving examples are known.


'Little Richard'

Now one of the most popular Sweet-gum clones in New Zealand (though believed to be of Australian origin), ‘Little Richard’ is described as dwarfish but of a neat, upright habit, with small leaves that turn red and orange in autumn (Hatch 2018–2020).


'Longworthii'

Found by Joseph Longworth near Cincinnati, Ohio, and described by Andrew Fuller in Practical Forestry in 1884, ‘Longworthii’ seems to have been a distinctive sport with forward-pointing lobes to its leaves which were carried on exceptionally long stalks. It appears lost to cultivation (Hatch 2018–2020).


'Midwest Sunset'

‘Midwest Sunset’ was selected by the Warren and Son Nursery in Oklahoma in the 1960s (Santamour & McArdle 1984), but was rejected after tests in Texas and Illinois (Hsu & Andrews 2005). Oddly, perhaps, the same plant – or at least the same moniker – now appears in several nursery catalogues in the United Kingdom and the Netherlands, as much perhaps for its alluringly evocative sale name as for its autumn colours, which are described as a rich mixture.


'Moonbeam'

First distributed by the Duncan and Davies Nurseries in New Zealand in 1976 (Hatch 2018–2020), ‘Moonbeam’ is now available mostly in the United Kingdom. It is a variant on the ‘Aurea’ group (q.v.), whose yellowish young leaves fade through blotchy cream to pale green. Autumn colours are variously described as soft yellow, pink and red (Hsu & Andrews 2005).


'Moraine'

A clone selected in Indianapolis and distributed by Siebenthaler’s in Ohio from 1982 (Hsu & Andrews 2005), ‘Moraine’ is particularly hardy – a quality not particularly relevant to the Dutch and UK nurseries who now stock it. It is variously described as vigorous (Hatch 2018–2020) and as compactly ovoid (Van de Berk Nurseries), though it is at least possible for an ideal tree to be both. Its autumn colour is red, or sometimes a mix of different tints (Santamour & McArdle 1984).


'Naree'

Synonyms
Liquidambar styraciflua 'Naree Yellow'
Liquidambar styraciflua 'Naree Bright'

The yellow-leaved selection ‘Naree’ is supposed to have originated in Australia – though presumably not at tropical Naree in the interior of northern Queensland – and was sold by Junkers in the United Kingdom from 2002 (Hatch 2018–2020). It is a less vigorous tree than ‘Moonbeam’ (q.v.), and its rather small leaves stay yellowish through summer and may need protection from full sun (Hsu & Andrews 2005). Autumn colour is variously described as gold, red and pink.


'Oakville Highlight' (PBR)

An upright or fastigiate tree (Hatch 2018–2020), selected in Australia by Fleming’s Nurseries and now sold in the United Kingdom by Provender Nurseries. It is too early to compare it to existing fastigiate Sweet-gum sports (here discussed under ‘Slender Silhouette’).


'Paarl'

‘Paarl’ is sold by several nurseries in the Netherlands and the United Kingdom for its autumn colour and is variously described as narrow with erect branching, compact in habit and large-leaved. The original tree was found in the South African city of Paarl near Cape Town, and scions were sold by the German Lappen Nursery from 1990 (Ebben Nursery).


'Palo Alto'

Selected in California before 1961 by the Saratoga Horticultural Foundation (Hatch 2018–2020), ‘Palo Alto’ is now available in the United Kingdom and is represented by a 10 m specimen at the Sir Harold Hillier Gardens in Hampshire (Tree Register 2021). It is described as neatly conic (in youth), with small leaves that all turn orange red in autumn.


'Parasol'

Customarily top-grafted on a stem of the type, ‘Parasol’ differs from ‘Gum Ball’ and other ‘dwarf’ Sweet-gums in its branches that droop to form a broad canopy. In the late Alan Hardy’s Liquidambar collection at Sandling Park in Kent, it has made a rather striking specimen, much superior as a small weeping tree to the ‘Pendula’ beside it (q.v.). The leaves are deeply lobed (Hatch 2018–2020) and in autumn they turn yellow then dark red (Hsu & Andrews 2005).


'Pendula'

The original tree was found by Sara Crawford in 1935 near Hatton, Arkansas (Hsu & Andrews 2005). The branches droop at a narrow angle, forming a slender crown, but are particularly brittle (Dirr 2009). Autumn colour is described as scarlet. Planted by the late Alan Hardy in his Liquidambar collection at Sandling Park in Kent, in ideal soil and woodland shelter, this clone has made a very poor, malformed tree (Tree Register 2021).

‘Churchill’, sold by Arborvillage Farm Nursery in Missouri from 2008 and described as weeping (Hatch 2018–2020), may represent the same mutation.


'Penwood'

Awards
AGM

A selection made by Doug Harris at the Penwood Nursery in Hampshire for its long-lasting, wine red autumn colour, and also sold by Junkers from 2002. In the climate of southern England this display can be very good, though Eric Hsu and Susyn Andrews (Hsu & Andrews 2005) observe that it does not stand out among the various seed-grown Sweet-gums in the Savill Garden at Windsor Great Park.


'Roemer 4'

Synonyms
Liquidambar styraciflua 'Fame Forever'

A Dutch selection whose long- and narrow-lobed leaves turn red and purple in autumn; now widely sold around Europe.


'Rotundiloba'

Synonyms
Liquidambar styraciflua f. rotundiloba Rehder

‘Rotundiloba’ was found by R.E. Wicker near Pinehurst, North Carolina, and was described as f. rotundiloba by Alfred Rehder in 1931 (Dirr 2009); it has short round lobes instead of pointed ones. There is a large tree, over 24 m tall, in the Coker Arboretum at Coker Hill in the same state (Hatch 2018–2020). Since its discovery, this curious mutation has been sold under names including ‘Rotundifolia’, ‘Obtusifolia’ and ‘Obtusiloba’ (Hatch 2018–2020) and (in Australia) as ‘Purple Fall’ (Yamina Rare Plants). Apart from its curiosity value, the reason to grow this sport – especially in warmer climates – is that it is sterile, though it is a chimaera, and fruiting reversions are always liable to appear (Hatch 2018–2020). It develops an odd, straggly habit (Dirr 2009), and autumn colour is relatively poor. It is grown in the United Kingdom, where one in the Wynkcoombe Arboretum in West Sussex is more or less evergreen (Tree Register 2021). The odd leaf shape is unlikely to be considered beautiful, in comparison at least with the starry leaves of typical forms.


'Savill Torch'

‘Savill Torch’ was selected at the Savill Garden in Windsor Great Park, Berkshire, as the best specimen for its autumn colours in the Sweet-gum avenue, whose trees had been grown from seed in the 1930s or 1940s; it turned reliably red and gold. Grafts were planted in the Savill and adjacent Valley Gardens (Hsu & Andrews 2005), and the clone remains available in Belgium and the United Kingdom.

It is of course easier to select a tree for its habit and colour in youth than for its long-term form and reliability. The original ‘Savill Torch’ blew over in the ‘Great Storm’ of 1987 but was left in situ and resprouted. The regrowth itself collapsed in 2002, and the plant was removed (Hsu & Andrews 2005).


'Silver King'

Along with ‘Variegata’, whose leaves are yellow-splashed, ‘Silver King’ is to date the best-known variegated Sweet-gum; each leaf has a bold creamy white margin. (The 1971 edition of The Hillier Manual of Trees and Shrubs unfortunately described ‘Silver King’ under the heading for ‘Variegata’, creating confusion that is still to be entirely dispelled.) In autumn the leaf centre of ‘Silver King’ tends to turn yellow, and the white bits can go pink (Dirr 2009). Despite the variegation, the tree grows quite well and is almost spire-shaped at best; it seldom, if ever, seems to revert. An early planting at the Savill Garden in Windsor Great Park had reached 12 m × 27 cm dbh by 2010 (Tree Register 2021).

‘Manon’ (‘Albomarginata Manon’) may represent the same sport, though the RHS suggests this is a variant name covering more than one clone, and trees sold as ‘Manon’ in Italy lack any variegation (Hsu & Andrews 2005). ‘White Star’, sold in the United Kingdom from 2006 and represented at the JC Raulston Arboretum in North Carolina by a plant sold by local nurseryman Ben Brown in 2002 (Hsu & Andrews 2005), is described as perhaps brighter, but can burn in strong American sun and, as it matures, it produces fasciations with small, deformed leaves (Hatch 2018–2020). Another sale name for a sport of this group is ‘Argentea’ (Hatch 2018–2020).


'Slender Silhouette'

Synonyms
Liquidambar styraciflua 'Shadow Columnar Form'

Awards
AGM

‘Slender Silhouette’ is probably the best clone sold so far of a narrowly fastigate Sweet-gum with erect branches. It was originally distributed by Don Shadow’s Shadow Nursery in Kentucky (Hatch 2018–2020), and a large tree, 21 m tall, grows or grew at the Milliken Arboretum in South Carolina. At the Daniel Stowe Botanical Garden in North Carolina, a 14 m tree maintains a remarkably neat, narrowly columnar habit (Hatch 2018–2020). Until mature, the clone produces little fruit.

‘Slender Silhouette’ is now available in the United Kingdom and has been sold by Barcham Trees at large-standard sizes; street trees were being planted around Holloway in North London by 2018 (Tree Register 2021). It should, however, be borne in mind that fastigate trees develop weak forks and seldom remain robust in the long term, and that L. styraciflua remains a brittle tree even in the warmest regions of the United Kingdom. Also, the species is naturally almost spire-shaped in youth and at best keeps a long, straight bole, so that a fastigiate sport is not necessarily required to fit one among buildings.

Clones sold in Europe whose shape resembles that of ‘Slender Silhouette’ and that may represent the same mutation include ‘Simone’, available from Boskoop in 2011 (Hatch 2018–2020), and ‘Fastigiata’ or ‘Pasquali Fastigiata’, which are probably illegitimate names.

For fastigiate selections that are not quite so tightly columnar, see ‘Emerald Sentinel’, ‘Kia’, ‘Little Richard’, ‘Oakville Highlight’ and ‘Tirriki’.


'Stared'

‘Stared’ (a contraction of ‘star red’ that should be pronounced with two syllables) makes a neatly shaped tree whose red-stalked leaves have five or often seven remarkably narrow lobes with big lobules at their shoulders – a shape more likely to suggest a snowflake, though not in spring when they flush reddish or in autumn when they burn red and purple. Junker’s Nursery rates it the best of all Liquidambar styraciflua cultivars for the United Kingdom. The unusual leaf shape has led commentators to suggest that ‘Stared’ (and ‘Worplesdon’) represent hybrids with L. orientalis (Dirr 2009), but the existence of such crosses has never been proved.

‘Red Star’ (Hsu & Andrews 2005) is presumably the same tree, and ‘Stella’, also sold in the United Kingdom, the Netherlands and the Czech Republic, is certainly very similar.


'Thea'

A Dutch selection, whose leaves, with long central lobes (Hsu & Andrews 2005), turn reddish purple in autumn, like those of ‘Burgundy’. It has been available in the United Kingdom since at least 2002.


'Tirriki'

A form selected by R.W. Boden in Australia in 1968, along with ‘Kia’, for its broadly conic habit and uniform red autumn colour (Hatch 2018–2020). ‘Tirriki’ is said to mean ‘flame of fire’ in an indigenous Australian language.


'Variegata'

A Liquidambar with leaves splashed and sectored in yellow was first described, under the name ‘Variegata’, by C.G. Overeynder from the Boskoop nurseries in 1880 (Sieboldia, 6 (35), p. 273). Since then, similar trees have been sold under a variety of different names, but it is quite likely that they all represent the same mutation – which can express itself differently from tree to tree and, indeed, from leaf to leaf.

The form was championed (as ‘Golden Sweet-gum’) in the United States by Ed Scanlon, whose nursery business, E.H. Scanlon and Associates in Ohio, first sold the tree under the illegitimate name ‘Aureum’ in 1962. (This was not the same plant as the yellow-leaved ‘Aurea’, q.v.) In 1967 Scanlon changed the sale name to ‘Variegata’, probably suggesting that his stock had derived from the original Dutch clone (Santamour & McArdle 1984). With its relatively low proportion of variegation per leaf, ‘Variegata’ grows almost as freely as the type, and a tree in Seattle, perhaps sourced from Scanlon (Jacobsen 2006), was 20 m tall by 1995 (Van Pelt 1996). With its rather glossy foliage, ‘Variegata’ makes a more attractive foliage plant than many a similar sport and is also good in autumn, when the yellow bits of the leaf tend to turn pink.

In the United Kingdom, ‘Variegata’ also grows well, into a conic tree at its best, and had reached 18 m at the Sir Harold Hillier Gardens by 2017 and 17 m at Tilgate Park, a public park in Crawley, West Sussex, in 2020 (Tree Register 2021). Its cause was not helped in this country by confusion in early editions of The Hillier Manual of Trees and Shrubs, in which the white-variegated ‘Silver King’ was described under the name ‘Variegata’; the Royal Horticultural Society now recommends the cumbersome name ‘Variegata Overeynder’ for the true, yellow-splashed form. In the last couple of decades, it has become more widely available, including at large-standard size.

Other sale names for what is probably the same tree include ‘Aurea Variegata’ (Dirr 2009), ‘Foliis Aureo-Variegatis’, described in Weimar in 1889 (Santamour & McArdle 1984), GOLD DUST® (‘Goduzam’), patented by the Lake County Nursery in Ohio in 1979 (Santamour & McArdle 1984), ‘Gold Star’ (‘Goldstar’), which is possibly more heavily variegated (Dirr 2009), and ‘Golden’ (Hatch 2018–2020).


'Ward'

Synonyms
Liquidambar styraciflua CHEROKEE™

A clone selected by Earl Cully at Jacksonville, Illinois, probably as early as the 1960s, for its good, narrow form, its sparse seed production, its hardiness (to USDA Zone 5) and its dark red autumn colours (Dirr 2009).


'Wisley King'

Scions from the original tree in Seven Acres at the RHS Garden Wisley in Surrey, which was 14 m × 64 cm dbh in 2017 (Tree Register of Ireland 2021) are now available in the United Kingdom. The original’s autumn colour is a rich mix of purplish crimson, scarlet and gold.


'Woorby Rose'

A Dutch or Belgian selection with rich red autumn colour, which is now available in the United Kingdom. The sale names ‘Woorby Rose’, recommended by the Royal Horticultural Society (Royal Horticultural Society 2021), and ‘Worby Rose’ are about equally frequent, and it is unclear which is correct.


'Worplesdon'

Awards
AGM

‘Worplesdon’ was selected in the United Kingdom by George Jackman and Son of Woking in 1968 from a tree in the Surrey village of Worplesdon (Hsu & Andrews 2005). It has become one of the commonest and most distinctive Sweet-gum clones grown in the United Kingdom. The leaves are small, with narrow lobes and big lobules at the shoulders; it is a relatively slow tree, often with a low, twiggy and untidy habit in youth, making it perhaps more suitable for the smaller garden. These combined characteristics have led many commentators to suggest that it represents a hybrid with Liquidambar orientalis, a hypothesis rejected by Eric Hsu and Susyn Andrews (Hsu & Andrews 2005). Unlike L. orientalis, ‘Worplesdon’ flowers and fruits freely in England’s cool summers. Autumn colour can vary from orange to red and purple, perhaps suggesting that more than one variant may now be in commerce (Hsu & Andrews 2005), but tints are bound to vary from season to season and from site to site anyway. Grown in an alkaline soil (Hsu & Andrews 2005), it will tend to disappoint, like most Sweet-gums, and merely turn brown.


'Worplesdon Variegated'

Synonyms
Liquidambar styraciflua 'Variegated Worplesdon'

This clone with a creamy white marginal variegation (like that of ‘Silver King’, q.v.) was bred in 2002 by the RareFind Nursery in New Jersey from ‘Worplesdon’, using tissue culture (Hatch 2018–2020). It is described as densely globose, like ‘Gum Ball’ (Hatch 2018–2020), and shares the small, intricately lobed leaf of ‘Worplesdon’; one online image suggests that, in Connecticut at least, it can make an attractive foliage plant.