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Taxodium distichum
Sponsor
In memory of Robin Herbert CBE VMH
Credits
Owen Johnson (2026)
Recommended citation
Johnson, O. (2026), 'Taxodium distichum' from the website Trees and Shrubs Online (treesandshrubsonline.
Common Names
- Swamp Cypress
- Bald Cypress
- Baldcypress
Synonyms
- Cupressus disticha L.
As treated here Taxodium is a monospecific genus. A full description reflecting the diversity of the species is provided in the genus article. Three varieties are recognised; the following description applies to var. distichum only. For the other varities see individual sections below on this page.
A tree to 50 m tall; bark reddish to grey-brown, with quite shallow vertical or interlacing ridges; lateral roots near water growing ‘knees’ profusely in warmer areas. Leaves and side shoots shed in late autumn to mid winter; side shoots spreading or drooping, their leaves more or less pectinate in 2 ranks; leaf c. 5–17mm long, the base of the free portion pinched and twisted. (Watson & Eckenwalder 1993).
Distribution United States Alabama, Arkansas, Delaware, Florida, Georgia, Illinois, Indiana, Kentucky, Louisiana, Maryland, Mississippi, Missouri, New Jersey, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, Virginia
Habitat Beside and in rivers whose waters are rich in silt; lake margins and swamps, occasionally in slightly brackish water; to 160 m asl (but to 500 m in Texas). Commonly associated species include Nyssa aquatica, N. biflora, Magnolia grandiflora, M. virginiana, Fraxinus spp. and Quercus spp.
USDA Hardiness Zone 4
RHS Hardiness Rating H6
Conservation status Least concern (LC)
Taxodium distichum var. distichum – the variety to which the above description applies – stands as the typical form of its species through historical accident: it was the first form to be introduced to northern Europe and the first to be described to science. In many ways, all three of this species’ very different varieties are equally significant, but the precedence given to var. distichum does seem somewhat appropriate as it the most abundantly distributed form in the wild, and, within a conifer species uniquely adapted for growing in standing water, it is the most specialised variety.
No hardy tree is more fully aquatic: although the seed can only germinate on dry land, and adult plants need the water to recede for at least a few weeks each summer, Swamp Cypresses are able to survive in floodwaters three metres deep, and in lowland rivers that can flow at 7 km per hour (Wilhite & Toliver 1990). Growing in these conditions the lower bole becomes massively flared or even bulbous, a feature shared by the two other large and long-lived trees that can be found alongside Swamp Cypress in the wild, Nyssa aquatica and N. biflora. (In cultivation elsewhere in the world, these species are yet to show a similar flare.) Unlike Nyssa, the lateral roots of Taxodium also throw up numerous stalagmite-shaped hollow ‘knees’ whose height tends to mark the maximum average floodwater level. These ‘knees’ are sometimes known as pneumatophores, a word originally describing the similar but more snorkel-like features which grow from the roots of the subtropical Black and Grey Mangroves (Avicennia germinans and A. marina) and which demonstrably serve these permanently submerged roots with air. Most experiments have so far failed to show that Swamp Cypress ‘knees’ share a similar physiological role; rather, the roots are instead kept aerated by gaseous exchange within the foliage, as in most other trees. Eventually, Swamp Cypresses growing in ground that never floods may start to grow ‘knees’ but they are produced most abundantly wherever soil meets deep water, and as palisades around trunks growing within rivers. These are just the places where an engineer would drive in piles to stabilise a bank, and the main role of the ‘knees’ seems to be to prevent the trees’ anchor-roots from getting undermined by strongly-flowing floodwaters (Martin & Franke 2015). Although the ‘knees’ are among this species’ most interesting and eyecatching features, they can also become a nuisance in lawns or paths, and one objective in the Chinese breeding programme of var. distichum and var. mexicanum has been to produce potential street trees which never grow knees (Creech 2022).
Wild seedlings need moist but not flooded ground in which to germinate in summer; the seedling then has to grow fast enough for its topmost foliage to remain above the winter floodwater. In the wild, seedlings can grow in wet mud or in sphagnum beds, but if these substrates dry too much the seedling will die. These niche adaptations make it perhaps surprising that Taxodium distichum is one of relatively few trees from the eastern United States – and perhaps the only one with such a southerly distribution – that is able to self-seed in north-west Europe. Conversely, it could be argued that it is able to do so because it can exploit conditions no European tree will tolerate – and because the resultant saplings grow in such unconventional places that it is immediately clear to the observer that nobody will have planted them there. (It should also be pointed out that grown from seed in standard nursery conditions, good seed will germinate readily without any special treatment – T. Christian, pers. comm. 2026). Examples of self-seeded trees in south-east England have included a young tree growing in shallowly-flooded former gravel workings at Thorpe in Surrey in 2000 and one in an old clay pond at Hellingly Country Park in East Sussex in 2019 (pers. obs.). In areas with longer and warmer summers and where seedlings can grow faster, the species naturalises more readily; places where Swamp Cypresses are starting to behave almost as they do in the wild include the floodplain of the river Körös in Szarvas, Hungary (T. Christian pers. obs. 2019), at the Veliko Ratno Ostrvo nature reserve in Belgrade, Serbia (Sijacic-Nikolic et al. 2011) and in Lake McLaren near Tauranga in New Zealand’s North Island.
Swamp Cypress is native to hurricane-prone areas, but the same adaptations that prevent the tree from getting swept away by floodwater also make it very windfirm; this is one of the least likely of trees ever to blow down. Partly because the window of opportunity needed for seedlings to germinate can be so narrow, and may only open at distant intervals, Swamp Cypresses have evolved to be among the longest-lived of trees; their timber is exceptionally durable, but, as an adaptation to surviving the occasional hurricane or tornado, it is also quite weak; trees sacrifice their branches and, unlike most conifers, are able to resprout from old wood. Consequently, the approximately spire-like shape of young plants is quickly lost and the mature crown becomes broad and irregular. This frailty can make Swamp Cypresses particularly ‘untidy’ trees in a formal setting; they tend to shed bits of themselves in every minor gale – but, as the author can attest, these fallen branches do at least offer a more or less continual source of good firewood.
This striking tree was among the first to be introduced from North America to northern Europe. It was grown in England by John Tradescant the Elder, who died in 1638, at his wide-ranging museum and plant collection ‘The Ark’ at Lambeth (now in south London; Parkinson 1640): this was over a century before Europe’s only native deciduous conifer, the larch Larix decidua, became at all a familiar tree in Britain. Although Swamp Cypresses are potentially long-lived trees in the wild, this does not appear to be the case in latitudes far to the north of the native zone, and Parkinson’s original has long since gone; indeed, only about a fifth of the specimens reported by Loudon (1838) in collections in Britain and Ireland were known to survive less than two centuries later (Tree Register 2025).
The oldest known Swamp Cypresses in England today were planted in the mid 18th century at Syon Park (now in west London) and at Painshill Park in Surrey. One of the Syon trees, growing on the bank of the private fishing lake, is the UK champion, with a trunk 2.45 m broad below the spring of several massive branches – a habit probably reflecting frost-damage from this tree’s youth during the height of the ‘Little Ice Age’. The two specimens on the lake dam at Painshill are only half the girth, and in complete contrast they must count as the most perfectly shaped large Taxodium in Britain. The microclimate of Painshill is similar to that of Syon, so this contrast in appearance is presumably due to the different origins of these trees. Another huge lakeside specimen at Burwood Park, also in Surrey, much broken but with a short bole 1.9 m thick in 2006, lacks a known history but may be as old, since its girth has only increased by 15% since 1947. One with a trunk 2.04 m thick in the same year, situated further west in moist, rich soil in a garden at Wimborne in Dorset, is growing considerably faster than this (Tree Register 2025).
Among wild populations, the tallest Taxodium distichum var. distichum on record is a tree that measured 44.11 m tall in 2003, at Carter’s Grove, Virginia; the largest recorded was 25 m tall, with a canopy spread of 26 m and a staggering dbh of 5.21 m in 2000, growing on Cat Island, Louisiana. In hurricane-prone areas tops are regularly broken and here it is unusual for trees to exceed 20–30 m (Earle 2026).
As a wild plant, Taxodium distichum var. distichum is distributed over a vast area across several quite different climatic zones. In the deep south – where it is virtually emblematic of hot, sticky swamps where everything is dripping with Spanish Moss (Tillandsia usneoides) – the growing season lasts virtually all year with average winter minimum temperatures of c. 4°C; at the northern end of its range in southern Illinois the growing season is reduced to about 190 days and (histroical) average winter minimum temperatures are in the region of –18°C (Wilhite & Toliver 1990). Despite these very different winters, the whole range has an important common theme: hot summers.
In common with most long-lived conifers, Taxodium distichum has retained a capacity to survive even greater winter cold than it experiences within parts of its current natural distribution, but only where summers are sufficiently warm. Plants from the northern part of the range are considered hardy to Zone 4 in interior areas of the northern United States and southern Canada, where they are helped by plenty of summer heat, but the species has failed near the east coast in Zone 5 at Orono, Maine (Dirr 2009). Conversely, var. distichum can also thrive in subtropical or even tropical climates, such as northern Queensland, Australia (Wikipedia 2024) and parts of South Africa (Trees South Africa 2024). This need for summer heat renders Swamp Cypress an excellent ‘tree thermometer’ when cultivated in cool-summer regions. In Britain, dimensions like those described above will only be attained in the hottest parts of south and east England; in northern England, Swamp Cypress is still a happy looking tree but grows too slowly to have acheived massive dimensions as yet; in Scotland, it can make a good tree in favourable sites as far north as southern Perthshire, but beyond here it struggles to reach tree size at all, nor is it overly fond of the cool, wet, west coast (Tree Register 2025). Anybody in want of a deciduous conifer tolerant of wet soils for cool-summer regions would be better advised to plant Metasequoia.
The warmer summers of mainland Europe have allowed Swamp Cypresses to thrive even better, even in areas that can experience significant winter cold. The European champion, at Marchienne Castle in Belgium, has a short but good bole 2.9 m thick, while the tallest, at Arboretum Balaine near the geographical centre of France, is 41 m tall (Monumental Trees 2024). These dimensions already compare favourably with those achieved in the species’ native range, where the measured girth of the bole is often inflated by the basal flare and by low forks.
One reason why cultivated plants have flourished so well is that, unlike nearly all wild trees, they grow in rich but well-drained garden soils. It is a common misconception that in order to thrive, Taxodium distichum needs a wet soil, or a nearby body of water. It is certainly among the best trees to plant in such difficult sites but the same general toughness that allows it grow in standing water means that, once established, it is well able to cope with dry sites, and indeed with the dry, compacted soils under urban streets. Some of England’s largest grow on soils derived from the notoriously free-draining Bagshot Sand beds of Surrey and Hampshire, including the huge and conspicuous tree planted in 1828 in the tiny garden of ‘Gothic Cottage’ on Woodhayes Road in central Wimbledon (now in west London). Fine examples may also be found growing in well-drained soils in several southern European cities, such as Florence and Seville, where the summer heat can be most intense (T. Christian pers. comm. 2026).
In recent years several British growers have experimented with establishing Taxodium distichum in containers, and then partially submerging those containers in (freshwater) lakes, ponds and river margins. Several trees planted this way in the lake at Bedgebury National Pinetum, Kent, UK are establishing well but do not exhibit such fast rates of growth as youngsters planted on dry land (D. Luscombe, pers. comm. 2025). Much older examples of trees planted in shallow waters may be found at the edge of Lake Como at Villa Melzi, Bellagio, Italy (T. Christian, pers. comm. 2025, and see image below).
Winters in northwest Europe tend now to be milder than those experienced by Swamp Cypress across much of its temperate range, and in vigorous young specimens leaf fall can be delayed until Christmas. These trees still put on a good colour show before the leaves finally drop, and this is even more welcome for occurring in the darkest days of the year, but in even milder conditions the variety is likely to tend towards the evergreen behaviour of var. mexicanum.
Taxodium is sometimes described as calcifuge, which may have discouraged experimentation in dry, chalky sites. At Westonbirt National Arboretum in Gloucestershire, UK, its performance on a free-draining, fertile and moderately alkaline soil has been indifferent at best. But in the rich soils beside limestone-laden chalk streams in Hampshire and Kent it consistently thrives (Tree Register 2025). On the strongly alkaline soils found in many parts of Texas, chlorosis can often be observed (North Carolina Co-operative Extension 2021). Despite parts of its natural distribution including coastal estuaries, Swamp Cypress seems not to be particularly salt tolerant. It will not tolerate water containing more than 0.89% salt, and even much lower concentrations than this can have an adverse effect, especially on young plants (Wilhite & Toliver 1990).
Because the three varieties of Taxodium distichum behave quite differently in cultivation, each with its own unique set of characteristics, they each receive a detailed account on this page. In order to achieve a logical and uncluttered article structure we have omitted cultivars from this page, and treat them separately on the page ‘Taxodium distichum Cultivars’. The hybrid cultivars, the product of Chinese breeding programmes crossing var. distichum and var. mexicanum, are also discussed on the ‘Taxodium distichum Cultivars’ page.
var. imbricarium (Nutt.) Croom
Common Names
Pond Cypress
Dwarf Cypress
Hat-rack Cypress
Upland Cypress
Vijvercipres
Synonyms
Cupressus disticha var. imbricaria Nutt.
Cupressus imbricaria Nutt.
Taxodium ascendens Brongn.
Taxodium ascendens var. erectifrons Beissn.
Taxodium distichum var. ascendens (Brongn.) Mast.
Taxodium distichum var. imbricatum hort.
Taxodium distichum 'Nutans' hort.
Taxodium imbricarium (Nutt.) R.M. Harper
Thuja lineata Poir.
A tree to c. 30 m; trunk less sharply and massively ridged than in var. distichum; ‘knees’ seldom produced. Bark brown to light grey, becoming more thickly furrowed. Deciduous shoots often erect, drooping as they lengthen, closely clad in mostly appressed and overlapping leaves c. 3–10 mm long, in shape mostly narrowly lanceolate and with the free portion not pinched or twisted at its base. (Watson & Eckenwalder 1993).
Distribution United States Alabama, Florida, Georgia, Louisiana, Mississipi, North Carolina, South Carolina, Virginia
RHS Hardiness Rating: H6
USDA Hardiness Zone: 5
Taxonomic note An unambiguous description of Taxodium distichum var. imbricarium as a variety (of Linnaeus’ Cupressus disticha) was published by the English botanist Thomas Nuttall, working in the United States in 1835. The word imbricarium is meaningless in botanical Latin and Nuttall had clearly meant to write imbricatum (the way that the variety’s leaves are imbricate or overlapping at their bases along the deciduous shoots is a useful feature differentiating var. imbricarium from var. distichum); for a long time it became conventional to correct Nuttall’s error, but the varietal name imbricatum was never validly published and the current rules of botanical nomenclature require that any orthographical errors in an original description have to be respected. Two years before Nuttall’s paper, the French botanist Adolphe-Théodore Brongniart had described the same taxon as a new species, Taxodium ascendens. T. ascendens therefore becomes this tree’s correct name if it is treated as a species, but since the combination T. distichum var. ascendens was not published until 1892, Nuttall’s name has precedence when the taxon is treated as a variety. An earlier description of the tree, made by Jean Poiret in 1817, does not have predecence because Poiret treated it as a species of Thuja rather than of any genus which is considered to be synonymous with Taxodium (Royal Botanic Gardens Kew 2025). Earlier still, William Aiton had described a specimen at Kew in 1789 as Cupressus disticha var. nutans (Aiton 1789). The description has long been dismissed as ambiguous, but an illustrated article from Curtis’s Botanical Magazine in 1866 by Sir Joseph Hooker clearly describes var. imbricarium (in its selection ‘Nutans’) and Hooker, as Director of Kew Gardens, knew that this tree was the one Aiton had described (Hooker 1866). In future, var. nutans may become the preferred name for the variety; for now, ‘Nutans’ refers to a clone or Group in which the deciduous shoots rise vertically and particulary neatly from the branches when young; these trees are also sparsely-branched and develop a thin, rather open crown, which is a useful point of distinction from other trees belonging to the variety.
Taxodium distichum var. imbricarium shares its natural range with var. distichum, though it does not extend inland up the Mississippi and Missouri rivers, nor northeastwards near the coast beyond Virginia (var. distichum extends to Delaware and New Jersey). It gets as far west as coastal Texas, where var. imbricarium seems known by a single tree at Shangri La Gardens, Orange, which is believed to be over a thousand years old (Creech et al. 2011). Within this common zone, the two varieties sometimes grow side-by-side, and can even merge one into the other, but var. imbricarium is generally a smaller tree which is adapted to less nutrient-rich habitats. In the Piedmont region, var. distichum is characteristic of the ‘red’ or ‘brownwater rivers’ whose floodwaters carry quantities of fertile silt, while var. imbricarium can be found along the ‘blackwater rivers’ whose waters are slower-flowing and nutrient-poor; it is also characteristic of pocosins, which are strongly acidic bogs in the Atlantic coastal plain. The range of var. imbricarium extends into poorly-drained pinewoods on acidic soils and into lakes away from the major river systems. Being less adapted to growing within fast-flowing flood-waters, the roots of var. imbricarium seldom produce the ‘knees’ which are such a feature of var. distichum. But because the range extends into fire-prone pinewoods, the bark of older examples of var. imbricarium is characteristically thicker and more coarsely ridged, giving it better insulating properties (Watson & Eckenwalder 1993; Wilhite & Toliver 1990) – a feature yet to be seen within the much younger cultivated population in Europe.
As a somewhat smaller and less imposing tree, Taxodium distichum var. imbricarium has never found quite the same popularity as an ornamental as var. distichum, either in Europe or outside its natural range in North America. Within its native range, however, it is an extremely popular tree (Earle 2026), with a steadily increasing range of cultivars available (for all cultivar entires, see the page ‘Taxodium distichum Cultivars’). With its even more delicate and feathery qualities, the foliage of var. imbricarium is at least as attractive as that of var. distichum and yet so different that the casual observer may not even guess the two forms are closely related. (It is interesting that the Swamp Cypress’ nearest living relative, Glyptostrobus pensilis from southern China, can display both these foliage types on the same tree).
The introduction of var. imbricarium to Europe is forgotten; an example at Kew was described by William Aiton in 1789 but its origin went unrecorded (Aiton 1789). Sir Joseph Hooker’s description and illustration of this specimen in Curtis’s Botanical Magazine in 1866 (Hooker 1866) shows clearly that it represented the variant or clone ‘Nutans’, a slender, sparsely-branched tree most notable for the way its young deciduous shoots stand in neat vertical ranks above the twigs. This represents one end of a continuum of growth forms among wild trees; it is not clear if Aiton’s tree at Kew was a seedling that happily represented this form, or whether some selection had already taken place within European gardens.
A var. imbricarium, perhaps not ‘Nutans’, was being grown by Louis Claude Noisette in France in 1817 (Lamark & Poiret 1817). Adolphe-Théodore Brongniart’s description of Taxodium ascendens in France in 1833 more clearly indicates the adpressed leaves of var. imbricarium and also the erect shoots of ‘Nutans’ (Brongniart 1833).
It seems probable that, in addition to being a slower tree than var. distichum, var. imbricarium is less likely to prove very long-lived in cultivation; historically, it was also more likely to be hurt by the late spring frosts so characteristic of the UK climate (Mitchell 1972). In the United States, there seems little evidence that these two varieties differ much in hardiness, although inland, northerly provenances of var. distichum – from Missouri, Illinois or Indiana – should be expected to show better adaption to intense winter cold.
The largest examples of var. imbricarium in Europe are certainly overshadowed by the giant stature already attained in suitable places by var. distichum. One at the Hortus Botanicus at Leiden in the Netherlands (pictured below) has a trunk 94 cm thick, while an example at Arboretum Châtenay-Malabry in France is 27 m tall (Monumental Trees 2024); in the UK a new champion, 20.6 m × 87 cm dbh, was discovered in a small Hampshire garden by volunteer recorder Hugo Egleston just as the author was preparing this account (Tree Register 2025). A much larger tree at the Weizigtpark in Dordrecht (the Netherlands; 25 m × 1.6 m dbh) has always been treated as var. imbricarium but in terms of its foliage is more like an unusually short-leaved var. distichum; a similar tree not far away at Hof te Dieren is even larger at 26 m × 1.88 m dbh (Monumental Trees 2024). These specimens are probably representative of some of the intermediate forms which can be found within the wild populations of Taxodium distichum (M. Frankis in Monumental Trees 2024).
There will be just a few special conditions in which var. imbricarium is able to outgrow var. distichum. One such site is a dry, clay hilltop at Beauport Park, East Sussex, UK, where the two varieties were planted side-by-side along the entrance drive, probably around the end of the 19th century; here, var. imbricarium also remains green for longer into autumn (pers. obs.).
var. mexicanum (Carrière) Gordon & Glend.
Common Names
Mexican Swamp Cypress
Montezuma Cypress
Ahuehuete
Ciprés
Synonyms
Taxodium distichum var. mucronatum (Ten.) A. Henry
Taxodium huegelii C. Lawson
Taxodium mexicanum Carrière
Taxodium montezumae Decne.
Taxodium mucronatum Ten.
Taxodium virens Beissn.
A tree to 50 m; trunk strongly flared when growing in water; crown often much-branched and spreading. Bark grey to reddish, developing shallow and mostly vertical, peeling ridges; small branches often pendulous. Side-shoots and leaves marcescent, persisting for a year or shed in cold winters or in the dry season; leaves c. 4–11 mm long, spreading in two flat ranks from the deciduous shoots. Pollen cones borne in long lax panicles c. 13–25 cm long. (Earle 2026; Fu et al. 1999).
Distribution Guatemala Huehuetenango Department Mexico Chiapas, Coahuila, Distrito Federal, Durango, Guanajuato, Guerrero, Hidalgo, Jalisco, México, Michoacán, Morelos, Nayarit, Nuevo León, Oaxaca, Puebla, Querétaro, San Luis Potosí, Sinaloa, Sonora, Tabasco, Tamaulipas, Tlaxcala, Veracruz, Zacatecas United States In the far south of Texas and in a few canyons in New Mexico
RHS Hardiness Rating: H4
USDA Hardiness Zone: 7
Taxonomic note Gordon and Glendinning’s Taxodium distichum var. mexicanum is the earliest description of this taxon at varietal level (1858), although if the taxon is treated as a species, Michele Tenore’s T. mucronatum has precedence since it was published five years earlier. Two years earlier still, Scottish nurseryman Peter Lawson had published the name T. huegelii, but his description was overlooked until the 21st century. González-Elizondo & González-Elizondo (2022) have proposed the conservation of the name T. mucronatum (for this taxon treated at species level), partly because Lawson’s description was felt to be too vague (Royal Botanic Gardens, Kew 2024; Earle 2026).
Whereas Taxodium distichum var. imbricarium occupies the same general area as var. distichum and is readily distinguished by its appearance and its preference for nutrient-poor sites, var. mexicanum is distinct mostly in terms of its disjunct range. All three varieties are native to Texas, but there is a big gap between the areas occupied by var. distichum (and perhaps just one tree of var. imbricarium) towards the north, and var. mexicanum around the Mexican border along the Rio Grande. In general appearance var. mexicanum closely resembles var. distichum: it is equally gigantic and perhaps as long-lived, and along the deciduous shoots its leaves are arranged in two flattened ranks. In general, var. mexicanum is almost evergreen (technically marcescent, shedding its old shoots just as the new ones expand), but can become leafless during the winter dry season in parts of the south, and when temperates fall unusually low in the north. Var. mexicanum is less specialised than var. distichum for growing in much-flooded sites and very seldom produces any ‘knees’. It is hard to define any other features to differentiate var. mexicanum from var. distichum, but in the former variety the stomata are about equally distributed on both sides of the leaf rather than being concentrated underneath, the female cones tend to be marginally smaller and the male flowers can be carried in longer panicles (Earle 2026; Fu et al. 1999). Var. mexicanum often makes a more spreading tree with less of a central axis, and its minor branches can weep almost with the panache of a Weeping Willow (Salix × sepulcralis ‘Chrysocoma’). The Mexican name Ahuehuete derives from the indigenous Nahuati language, translating as ‘old man of the lake’ (Earle 2026).
A study of DNA sequences and terpenoids in the varieties of Taxodium distichum by Adams et al. (2012) confirmed their fairly close allegiance, but showed that the southernmost populations of var. mexicanum, in Guatemala’s Huehuetenango Department and Oaxaca and Chiapas Provinces in south Mexico, provide the species’ most genetically distinct subpopulation. Since this distinctness is not yet reflected in the species’ taxonomy, and may not be reflected in any macroscopic features, it is hard to determine which – if any – examples of var. mexicanum in temperate collections represent this southern material. The world’s largest-girthed tree, the ‘Arbole de Tule’ in the town of Santa Maria del Tule, Oaxaca, belongs to this southern race; it was propagated several times in recent years, though, as with many trees of great age, vegetative propagation has proved extremely inefficient. David Creech was part of a team who collected a few seeds from the Arbole de Tule in 2013; one of these seedlings was vegetatively propagated and distributed to various institutions in the southern United States under the name ‘Oaxaca Child’ (Creech 2016).
The bole of the Arbole de Tule has a girth of 58 m, although this figure is greatly inflated by the buttresses supporting the major limbs and the way that the tree in its youth may have forked almost from the base; there has been speculation – common to many specimen trees of this shape – that it originated as several individual plants that had somehow fused, but in this case DNA sampling has discredited such a hypothesis (Earle 2026). Certainly, the Arbole de Tule’s estimated mass of 630 tonnes cannot compare with that of the oldest Giant Sequoias (Sequoiadendron giganteum), which with their long columnar boles can exceed 2000 tonnes. The Arbole de Tule may not even be the oldest tree of its variety; current estimates suggest it is 1400–1600 years old (Creech 2016). A tree at the pilgrimage site of Chalma in Mexico State is supposed to be 2270 years old, although the oldest specimen to be reliably dated using dendrochronologic analysis, at Los Peroles, San Luis Potosi State, is ‘only’ 1140 years old (Earle 2026).
The various and relatively small zones to which var. mexicanum is native lack the seasonally flooded river plains and deltas where var. distichum finds its home. Var. mexicanum is instead a characteristic tree of mountain streams and riverbanks, and of canyons where water only flows in the wet season, sometimes forming pure stands but more often growing alongside many other trees including planes, poplars and figs. It also inhabits upland marshes and lake fringes, and the Aztecs employed it to drain such sites on a vast scale, planting it to form palisades behind which they piled earth until the ground was dry enough to farm and to build on. Traditionally, the bark was used as a diuretic, the leaves to treat scabies and the resin to treat ulcers, skin ailments and toothache. At the Parque Nacional El Contador near Mexico City, the Aztec Emperor Montezuma created a rectangular 800 × 400 m park entirely planted with Taxodium, which became the variety’s type locality. But by 2005 most of the garden had been destroyed, and only one of Montezuma’s trees was just alive, surrounded by burnt-out stumps (Earle 2026).
Although the absence of a concentrated display of autumn colour might be held against var. mexicanum in an ornamental role, the variety does have several other advantages over var. distichum. It is slightly more tolerant of salt in the soil – a problem which can build up in irrigated land – and it seldom develops chlorosis in alkaline conditions. Given prolonged warmth, it can grow faster, with the clone ‘Oaxaca Child’ reported to grow at nearly two metres a year in the southern United States (Creech 2016); with its durable timber, var. mexicanum has therefore become a significant forestry tree in subtropical areas. Swamp Cypress ‘knees’ can become spectacular features, but in more formal situations they can act as trip hazards and erupt through tarmac, making their absence in var. mexicanum another potential attraction. In China, var. mexicanum has become extraordinarily popular as a garden and street tree – despite the existence of the indigenous and more manageably sized Chinese Swamp Cypress Glyptostrobus pensilis, which is assessed as Critically Endangered in the wild. (Any Chinese author commenting on the abundant use of the Bastard Service Hedlundia thuringiaca as a street tree in the UK would probably feel obliged to make some identical comments about Britain’s endangered native Hedlundia microspecies). At Nanjing Botanical Garden since the 1980s, a breeding programme has attempted to produce superior Swamp Cypresses by crossing var. mexicanum with var. distichum, combining the vigour of the former with the latter’s typically straighter habit and resistance to Cercosporidium needle blight (Creech et al. 2011). Cultivars belonging here are listed in the ‘Taxodium distichum Cultivars’ article under the heading ‘Hybrid Cultivars’.
The winter hardiness of var. mexicanum presumably varies across its extensive natural range. Attempts to grow it at Kew through the 19th century met with failure (Bean 1914) and will have contributed to the idea that this is a tender tree unsuitable for northern Europe. (The Hillier Manual of Trees and Shrubs continues to suggest a grossly conservative RHS hardiness zone of 3, implying that it is unlikely to survive more than 5°C of frost – Edwards & Marshall 2019). However, another attempt to grow var. mexicanum next to the lake at Kew – received from the well-travelled English dendrologist Henry John Elwes in 1908 – has proved a triumph: by 2022 this specimen was 22 m tall with a trunk 1.3 m broad. It remains squatter and less straight than surrounding examples of var. distichum but its minor branches have adopted the beautifully cascading character shown by many – but not all – wild var. mexicanum. In 1906 Augustine Henry (Elwes & Henry 1906–1913) recorded its provenance in The Trees of Great Britain and Ireland, noting that it was one of two seedlings raised by Elwes from seeds brought from Oaxaca by Mr Marlborough Pryor in 1904. One was destined to be planted at Tregothnan, Cornwall, and the other “in the Temperate House at Kew”. It is not known when it was placed in its current position – or what happened to the Tregothnan plant.
Sadly, this single success story did nothing to promote the variety in Britain, and var. mexicanum seems not to have been reintroduced until the Royal Botanic Garden Edinburgh’s International Conifer Conservation Programme outstationed a few plants in 1992–93, including seedlings from the collection G&K 5287 (Royal Botanic Garden Edinburgh 2025). In the mild and humid microclimate of Fota in southern Ireland, G&K 5287 was 9 m × 25 cm dbh in 2017, but has been marginally outgrown by another ICCP planting at Exeter University in southwest England, where summers are a little warmer (Tree Register 2025). Three youngsters are also thriving in Cypress Valley at Bedgebury National Pinetum in Kent, a once-notorious frost-hollow (Tree Register 2025). Var. mexicanum became commercially available in the UK soon after this; one tree obtained as var. mexicanum is growing strongly in the more continental conditions of Lance Arthey’s Common Farm Arboretum in Suffolk, where it is largely deciduous. Meanwhile a partly evergreen Taxodium obtained as T. distichum at Dr Richard Ryder’s Dragon Field Pinetum in Devon may also represent var. mexicanum: Devon’s winters are usually mild, but remarkably for the region the Dragon Field is situated at an elevation of 330 m (Tree Register 2025). Commercial offerings in the UK in 2024 included the wild collection NJM 09–037 from 1190 m asl in eastern Durango (Royal Horticultural Society 2024).
Var. mexicanum is bound to grow even better in areas with longer and hotter growing seasons. Trees in southern Europe, probably nearing but not exceeding 200 years in age, include one of 37.2 m × 2.17 m dbh in the Jardines de Principe, Aranjuez (Spain), one of 25.6 m × 1.86 m dbh at the Giardino dei Semplici, Florence (Italy), another of the same size at Parc Beaumont, Pau (France) which shares the weeping habit of the Kew tree, and one of 33.5 m × 1.5 m at Quinta de Monserrate, Sintra (Portugal) (Monumental Trees 2025; Jacobson 1996).
Mexican trees began to be used for ornament in the United States at a more recent date; they were in California by around 1905, but have only become at all common in Texas, where they cope well with the often strongly alkaline soils (Jacobson 1996). Although the assessment by OIKOS Tree Crops that the variety could withstand –30°C in Michigan (Jacobson 1996) has to be considered suspect, var. mexicanum has certainly made a fine tree 17.5 m tall at the JC Raulston Arboretum in North Carolina, where –15°C is not uncommon (JC Raulston Arboretum 2025).
On the other side of the world, var. mexicanum also flourishes at the Sydney Botanic Gardens in Australia, and is commercially available in New Zealand (Leafland Wholesale Tree Nursery 2024).
