Acer saccharum Marsh.

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Credits

Dan Crowley (2024)

Recommended citation
Crowley, D. (2024), 'Acer saccharum' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/acer/acer-saccharum/). Accessed 2024-05-25.

Genus

  • Acer
  • Sect. Acer, Ser. Saccharodendron

Common Names

  • Sugar Maple
  • Rock Maple

Synonyms

  • Acer barbatum Michx.
  • Acer saccharinum Wangenh., not L.
  • Saccharodendron saccharum (Marshall) Moldenke

Other taxa in genus

Glossary

section
(sect.) Subdivision of a genus.
connate
Fused together with a similar part. (Cf. adnate.)
disjunct
Discontinuous; (of a distribution pattern) the range is split into two or more distinct areas.
herbarium
A collection of preserved plant specimens; also the building in which such specimens are housed.
hybrid
Plant originating from the cross-fertilisation of genetically distinct individuals (e.g. two species or two subspecies).
included
(botanical) Contained within another part or organ.
key
(of fruit) Vernacular English term for winged samaras (as in e.g. Acer Fraxinus Ulmus)
mesic
(of habitat or site) Moderately moist. (Cf. xeric.)
sensu stricto
(s.s.) In the narrow sense.
subspecies
(subsp.) Taxonomic rank for a group of organisms showing the principal characters of a species but with significant definable morphological differentiation. A subspecies occurs in populations that can occupy a distinct geographical range or habitat.
taxonomy
Classification usually in a biological sense.
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

Dan Crowley (2024)

Recommended citation
Crowley, D. (2024), 'Acer saccharum' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/acer/acer-saccharum/). Accessed 2024-05-25.

A deciduous tree to 30 m. Bark dark grey to greyish-brown, fissuring, sometimes deeply so, with age. Branchlets slender, smooth, greenish, turning orange to reddish-brown with age. Buds 0.6–1.2 cm long, acute, slightly pubescent, with four to eight pairs of imbricate scales. Leaves broadly pentagonal in outline, base cordate to truncate, three to five lobed, 7.5–15 × 20–24 cm, lobes apically acute or acuminate, margins remotely dentate with acuminate teeth, upper surface bright green, lower surface paler, glabrous, pubescent, or with tufts in vein axils; petiole 4–8 cm long, green, glabrous, often grooved, broadest at base; autumn colours yellow to deep red or scarlet. Inflorescence terminal or axillary, corymbose, pendulous. Flowers yellow, 5-merous, pedicels long and slender, sepals obtuse, greenish yellow, pubescent on the outer surface, petals absent, stamens seven or eight, inserted in the middle of the nectar disc. Samaras 3 to 3.5 cm long, wings spreading acutely. Nutlets rounded. Flowering April to May, before or with unfolding leaves, fruiting in October (Rehder 1927–1940; Sargent 1965; Elias 1980​​​​; van Gelderen et al. 1994).

Distribution  Canada New Brunswick, Ontario, Québec. United States Connecticut, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Maine, Maryland, Massachusetts, Minnesota, Missouri, New Hampshire, New York, North Dakota, North Carolina, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Vermont, Virginia, West Virginia, Wisconsin.

Habitat Lowlands on mixed soils (but not swamps), thriving on deep, rich, well-drained soils. A key component of eastern deciduous forests, associated species include Betula alleghaniensis, Fagus grandifolia, Prunus serotina, Quercus alba, Quercus rubra and Tsuga canadensis.

USDA Hardiness Zone 3

RHS Hardiness Rating H7

Conservation status Least concern (LC)

Taxonomic note The sugar maples (Acer Section Acer Series Saccharodendron) are a group defined largely on the characters of the flowers, which have connate sepals and are without petals (van Gelderen et al. 1994). Their taxonomy has long been disputed, and treatments are inconsistent between major works. In New Trees, Grimshaw & Bayton (2009) followed the late Peter Gregory’s advice to treat Acer saccharum as a widespread, polymorphic species comprising six subspecies in addition to the nominate subsp. saccharum. This was in line with the landmark study of Desmarais (1952) who based his treatment of the group principally on the type of outline leaves possessed, having collected single leaves from trees across the range of the group (465 localities), supplemented with study of herbarium material. The study concluded with the treatment of the following taxa as subspecies within A. saccharum: subspp. floridanum, grandidentatum, leucoderme, nigrum, saccharum, and schneckii. This greatly simplified the situation: by the early 1950s – when Desmarais undertook his study – the constituent taxa of the A. saccharum complex had been described in more than 97 different combinations (Desmarais 1952). Desmarais’s treatment was broadly followed by Murray (1975), who additionally assigned subspecific rank to A. brachypterum (now within A. grandidentatum), and treated A. skutchii at the same rank. Separately, Murray (1970) lists schneckii as a variety rather than a subspecies, as it was originally characterised by Rehder. This author also described a number of further taxa now confined to synonymy in several works (e.g Murray 1969; Murray 1975). In Maples of the World, van Gelderen et al. (1994) also followed Desmarais, adopting some additional combinations made earlier by other authors. However, this approach found little support in North America, with several authors since continuing to treat taxa at specific rank (e.g. Grimm 2002; Lance 2004; Kirkman et al. 2007). Yatskievych (2006), however, also followed Desmarais, drawing attention to intermediates between between A. saccharum and A. nigrum, in accordance with several other reports. Skepner & Krane (1997) concluded that these two taxa are genetically indistinct, with no barriers to gene flow, and thus ought to be treated as one and the same. More recently, Vargas-Rodriguez et al. (2020) and Weakley & Southeastern Flora Team (2022) have opted to treat the taxa within their respective study regions as distinct species, though the serious need for a comprehensive study using modern methods is widely acknowledged. Given these most recent interpretations, in the absence of a modern study, and in anticipation of an updated account in the Flora of North America, here we also treat the principal members of the complex as species, with Desmarais’s subsp. schneckii tentatively treated as a variety of A. saccharum. Following Vargas-Rodriguez et al. (2020), A. grandidentatum comprises var. sinuosum in addition to the nominal variety. See the individual species accounts for significant synonyms. A key to the species and varieties treated here, adapted from Grimshaw & Bayton (2009), is included below.

Acer saccharum is a long-lived, climax species of the mesic forests of eastern North America. Growing wild with numerous other plants renowned for their autumn colour, its seasonal colours are, in North America at least, ‘the standard by which all other trees are measured’ (Sternberg 2004), attracting seasonal visitors from across the globe. The sugar maple forests of New England are a popular destination for ‘leaf-peeping’ tours, while seasonal tourism in North Carolina is estimated to boost the Appalachian state’s economy alone by as much as $1 billion a year (Appalachian State University 2024).

This species is also the primary source of maple syrup, with Acer nigrum and A. rubrum also often used for this purpose (Perkins et al. 2022). Several other maple species are tapped for sugar, though are less commercially significant. While the United States was once the largest maple sugar producer, Canada is now the principle source globally, with the industry worth $1.35 billion in 2023 (Fortune Business Insights 2023). Aside from syrup and autumn colour, Acer saccharum produces timber valued for the production of sports equipment and musical instruments (Kurz 2003). The sugar maple leaf’s likeness adorns the Canadian flag, and the tree’s significance further south is acknowledged in its designation as the state tree of New York, Vermont, West Virginia, and Wisconsin.

In built landscapes in North America, the species is largely restricted to use in suburban areas, being intolerant of pollution, salt, compaction and extremes of heat and dry (Sternberg 2004; Dirr & Warren 2019). Rather, it favours moist, free draining soils, though can have a tendency to produce tight forks, leading to structural problems later on (F. de le Mota pers. comm. 2022). While shade tolerant, it prefers sunny conditions that enhance its autumn colour, though it can be prone to leaf scorch and tatter (Dirr & Warren 2019). Leaf toughness varies depending on provenance, and appropriate cultivar selection and siting is important. In some cases, Acer platanoides has been favoured as a replacement for poorly sited sugar maples (e.g. Schwets & Brown 2000), however that species has also become invasive in native sugar maple forest. The largest recorded A. saccharum grows in Maybrook, Virginia, with a girth measured in 2016 at 6.86 m (Monumental Trees 2024). It is rivalled by a Canadian individual, measured at 6.58 m girth in 2021, growing in Pelham, Ontario (Monumental Trees 2024).

Introduced to Britain in around 1735, Acer saccharum has remained uncommon here ever since. While it is capable of making a fine tree in form (and will do well further north than other eastern North American trees which demand more summer heat – Mitchell (1996) reported fine trees in Argyll, Perthshire, Fife, and even on the Isle of Lewis, albeit in woodland conditions), its autumn colour is never as strong and thus other taxa are often preferred. The current UK and Irish Champion for girth grows at Belton Park, Lincolnshire, measuring 1.15 m in diameter (The Tree Register 2023). The UK’s tallest specimen is a tree growing in the old maple collection in Westonbirt’s Silk Wood, measured at 25 m in 2014 (The Tree Register 2023). Several younger examples are also found at Westonbirt, including from seed collected in 2006 by Chris Reynolds and Dan Luscombe under CRDL (nos. 34 and 157, from West Virginia and the Smokey Mountains National Park, respectively. Two of the three ‘good, big trees’ at Eastnor Castle, Ledbury, reported by Mitchell (1996) were still extant in 2019 (T. Christian pers. comm.). At Rogów, Poland, specimens growing in an experimental forestry plot flower regularly but are yet to produce any fruit. However, in western Poland, in a slightly warmer climate, the species produces spontaneous seedlings (P. Banaszczak pers. comm. 2023).

Of the great many cultivars of the species, only a few are available in western Europe, the vast majority having been developed in the United States. Their attributes as described here thus relate largely to performance within North America. Of much interest to US sugar maple growers are plants originating from relict populations of the canyons of Caddo and Canadian counties, Oklahoma, from which various cultivars have been named. Collectively known as Caddo maple, and disjunct from the continous population of Acer saccharum, taxonomic placement of this ecotype remains unsatisfactorily resolved. Dent & Adams (1983) undertook a morphological study resulting in their placement within A. saccharum var. saccharum (A. saccharum sensu stricto, as treated here), though incorporating flavonoid data, Gelbach & Gardner (1983) concluded that the populations are a hybrid between A. floridanum and A. grandidentatum (the former sometimes treated within A. saccharum at the rank of subspecies – see taxonomic note). Several resources include the Caddo cultivars in listings for A. floridanum, though the balance appears to be with A. saccharum currently. They are tentitively included here, under Caddo Cultivars, and should be included in any future study on the sugar maple complex.

1aLeaf underside pale green to glaucous2
1bLeaf underside yellow-green7
2aLeaves large (≥ 10–15 cm)3
2bLeaves small (5–10 cm)5
3aLobe tips bluntly pointed, undersides pubescent and glaucousAcer skutchii
3bLobe tips attenuate, leaf undersides glabrous to pubescent4
4aLeaf undersides glabrous, or pubescent along the veins with appressed hairsAcer saccharum var. saccharum
4bLeaf undersides pubescent throughout, hairs upright or tangledAcer saccharum var. schneckii
5aLobe tips rounded to acute, leaf undersides glabrous to pubescent with long, forward-pointing hairsAcer floridanum
5bLobe tips rounded to obtuse, leaf undersides pubescent with short, spreading hairs6
6aLobes with prominent projections with large, blunt teethAcer grandidentatum var. grandidentatum
6bLobes without, or with few, prominent projections with rounded tipsAcer grandidentatum var. sinuosum
7aLeaves small (5–10 cm), undersides with soft appressed hairs, bark smooth, pale grey to chalky whiteAcer leucoderme
7bLeaves large (≥ 10–15 cm), undersides with stiff, short, erect hairs, bark rough, dark grey-brown to blackAcer nigrum

'Adirzam'

Common Names
Adirondak Sugar Maple

Synonyms / alternative names
Acer saccharum ADIRONDAK®

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

Introduced by Lake County Nursery, Ohio, in 1991, this is a compact clone with ascending branches. It reportedly has increased drought tolerance relative to typical Acer saccharum, and its dense foliage turns golden around two weeks later than other forms (Jacobson 1996).


'Alton Ogden'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

Named by Ohio nurseryman Ed Scanlon for Mr Alton Ogden of Flint, Michigan, in 1951 (Jacobson 1996). Widely described as ‘lyre-shaped’, it was thought no longer to be in cultivation by van Gelderen et al. (1994) and commercially extinct by Jacobson (1996).


'Arrowhead'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 4

According to van Gelderen et al. (1994), introduced by Carlton Plants, Ohio, in 1961, though Jacobson (1996) and Hatch (2021–2022) state Schichtel Nursery, New York in 1979 as its point of introduction. Of pyramidal form with a strong leader, hence the name, it attains 20 m and turns orange to red in autumn (van Gelderen et al. 1994; Jacobson 1996).


'Artis'

Synonyms / alternative names
Acer saccharum STEEPLE™

RHS Hardiness Rating: H7

A selection made by Michael Dirr and introduced via Athena Trees, Georgia (Hatch 2021–2022), ‘Artis’ has an upright form with a narrow crown and strong central leader (Dirr & Warren 2019). Heat resistant, with yellow to orange autumn colour, it reportedly does well in northern as well as southern states in the US (Dirr & Warren 2019).


'Bailsta'

Synonyms / alternative names
Acer saccharum FALL FIESTA®

RHS Hardiness Rating: H7

USDA Hardiness Zone: 4

Introduced by Bailey Nursery, Minnesota from a seedling grown in Oregon, ‘Bailsta’ has thick, durable leaves that turn yellow, orange or red in autumn (Hatch 2021–2022). It has a moderate growth rate and develops with a strong central leader (Dirr & Warren 2019).


'Bakharl'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

Introduced by Robert Baker of West Suffield, Connecticut, who made the selection from a local tree (Hatch 2021–2022). It has a dense crown with an upright, spreading form and autumn colours from yellow to purplish-red (Hatch 2021–2022).


'Bakrise'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

Another clone selected in 1993 by Robert Baker of W. Suffield, Connecticut, with bright red autumn colour (Hatch 2021–2022).


'Barrett Cole'

Synonyms / alternative names
Acer saccharum APOLLO®

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

A densely crowned, narrow clone of conical shape (Dirr & Warren 2019). Slow growing, it is recommended for use as a street tree and would equally suit smaller gardens, ultimately attaining only around half the size of typical Acer saccharum (Dirr & Warren 2019; Great Plant Picks 2020). In autumn it turns from bright yellow to red (Dirr & Warren 2019).


'Bonfire'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

Introduced by Princeton Nursery, New Jersey in 1977–78 according to Jacobson (1996) and Hatch (2021–2022), though according to van Gelderen et al. (1994) it was introduced by J. Frank Schmidt & Son in around 1965. Broader than most Acer saccharum selections, it is also faster growing. Suited to a range of growing conditions, with good heat tolerance, it turns a deep red at its autumn best, but only yellow to orange in some areas, including the American Midwest (van Gelderen et al. (1994); Jacobson 1996).


'Brocade'

Synonyms / alternative names
Acer saccharum 'Dissectum'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

Selected from a wild tree at Croton Falls, New York, and introduced in 1981 (Jacobson 1996). Its leaves are deeply cut and sometimes further sub-lobed (Jacobson 1996). It turns golden yellow in autumn (van Gelderen et al. 1994).


'Cary'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

Discovered in the Cannoo Hills, New York (now the Cary Arboretum) in around 1960, named for Mary Flagler Cary and introduced by Brooklyn Botanic Garden in 1974 (Jacobson 1996). Compact and slow growing, it has a narrow habit with leaves that persist for longer than other forms. These are smaller than typical Acer saccharum, though a specimen growing in Seattle was noted by Jacobson (1996) for normal-sized leaves.


'Coleman'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

Selected by R.M. Nordine of The Morton Arboretum, Illinois from a broadly columnar tree growing in Lake City, Minnesota, and named around 1958 (Jacobson 1996). Autumn colour is bright orange to red (The Morton Arboretum 2018).


'Commemoration'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

Selected by W.N. Wandell of Urbana, Illinois and introduced by Moller Nursery, Gresham, Oregon in around 1981 (van Gelderen et al. 1994; Jacobson 1996) Acer saccharum ‘Commemoration’ is a vigorous grower developing a dense rounded crown. It is noted for its foliage that resists leaf tatter and for good autumn colour, the glossy leaves turning yellow to orange in autumn (Jacobson 1996; Dirr & Warren 2019). Sometimes given as a cultivar, and sometimes as a trade designation, no alternative name to ‘Commemoration’ has been traced.


'Davey'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

A clone with rapid growth, developing a broad, dense crown, with dark leaves that turn yellow to orange in autumn (Jacobson 1996). It was introduced in around 1990 by Davey Nursery, Ohio (Jacobson 1996; Hatch 2021–2022).


'Endowment'

Synonyms / alternative names
Acer saccharum 'Endowment Columnar'
Acer saccharum 'HRI 1'
Acer saccharum 'Lanco Columnar'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

A tree with an upright habit, becoming narrowly oval with scorch-resistant leaves that turn bright orange-red in autumn (Jacobson 1996; Dirr & Warren 2019). Introduced in 1980–81 by Siebenthaler Nursery, Ohio (Jacobson 1996).


'Fairview'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

With strong growth developing an oval crown, its leaves turn orange in autumn (Jacobson 1996). Its bark is noted to be paler than that of typical Acer saccharum (van Gelderen et al. 1994; Jacobson 1996). Introduced by the A. MacGill & Son Nursery of Fairview, Oregon in 1980–81, for where it was named (Jacobson 1996).


'Fidcrezam'

Synonyms / alternative names
Acer saccharum FIDDLER'S CREEK™

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

A selection with deeply cut lobes, its leaves thicker than typical Acer saccharum and very durable, turning orange in autumn (Hatch 2021–2022). Introduced by Lake County Nursery, Ohio in 2005 (Hatch 2021–2022).


'Firehouse'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 4

Noted for its striking orange and red autumn colour, introduced by Greenleaf Nursery, US (Hatch 2021–2022).


'Flax Mill Majesty'

Synonyms / alternative names
Acer saccharum 'Majesty'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 3

Introduced by Flax Mill Nursery, New York in 1983, Acer saccharum ‘Flax Mill Majesty’ forms a large, vigorous tree with a symmetrical crown with dark green leaves that colour red to orange notably early (Jacobson 1996). Noted as well-suited to northern parts of the United States by Dirr & Warren (2019).


'Flower'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

Named around 1958 for H.C. Flower of Manchester, Vermont, from whose land it was selected from an exceptionally narrow tree (Hatch 2021–2022). Never thought to have been widely circulated, it was reported long-since commerically extinct in by Jacobson (1996) who cited a specimen with an 11 m spread, suggesting the attribute for which it was selected was soon lost.


'Globosum'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

A tree with a globose crown, as wide or wider than tall (van Gelderen et al. 1994; Jacobson 1996). It was found by W.K. LaBar, of Labar’s Rhododendron Nursery, Stroudsburg, Pennsylvania, in the mountains of North Carolina, and introduced by Kingsville Nursery, Maryland around 1942 (Jacobson 1996). It is usually top-grafted to produce a tree with a tight, rounded crown (Jacobson 1996). Its autumn colour is golden orange to red (van Gelderen et al. 1994; Jacobson 1996).


'Goldspire'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

Introduced by Princeton Nurseries, New Jersey, in 1973–74, this is the result of a cross between ‘Newton Sentry’ and ‘Temple’s Upright’ (Jacobson 1996). It has a compact form, with a more or less columnar crown, with leaves that resist scorch, turning yellow or orange in autumn later than most Acer saccharum selections (van Gelderen et al. 1994; Jacobson 1996).


'Green Mountain'

Synonyms / alternative names
Acer saccharum 'PNI 0285'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

Probably the best known Acer saccharum selection, ‘Green Mountain’ has a broadly oval crown and vigorous growth (van Gelderen et al. 1994; Jacobson 1996). Introduced by Princeton Nursery, New Jersey, 1964–65, it is tolerant of urban conditions and produces reliably fine autumn colour, from yellow to red (van Gelderen et al. 1994; Jacobson 1996; Dirr & Warren 2019).


'Hawkersmith 1'

Synonyms / alternative names
Acer saccharum AUTUMN FAITH™

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

A slow-growing tree with a dense, vase-shaped crown and bronze new growth (Hatch 2021–2022). Tolerant of heat and drought, it colours orange to red in autumn, a little later than most other selections (Dirr & Warren 2019). It also has a smaller ultimate size than most Acer saccharum selections, reaching little more than 10 m (Dirr & Warren 2019).


'Hiawatha 1'

Common Names
Oregon Trail Maple

Synonyms / alternative names
Acer saccharum OREGON TRAIL™

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

Selected from along the Oregon Trail in Hiawatha, Kansas, which is known as ‘The City of Beautiful Maples’ on account of significant plantings of Acer saccharum over several years (Grimm’s Gardens 2020). Heat resistant, OREGON TRAIL™ develops a rounded crown and has thick leaves with vibrant orange to red autumn color (Dirr & Warren 2019). It was introduced by J. Frank Schmidt & Son Co. in 2010 (Hatch 2021–2022).


'Jefcan'

Synonyms / alternative names
Acer saccharum UNITY™

RHS Hardiness Rating: H7

USDA Hardiness Zone: 3

Selected in Manitoba from a seedling of northern Minnesota origin, ‘Jefcan’ is thought by Dirr & Warren (2019) to be the most cold hardy of all Acer saccharum selections. It has a good growth rate and yellow, orange or red autumn colour (Dirr & Warren 2019).


'Jefselk'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 3

Selected by Jeffries Nurseries, Manitoba, from the Red River Valley in that province. It has a broad upright form and orange autumn colour, and is suggested for use in the Canadian southern prairies by those who introduced it (Jeffries Nurseries 2017).


'JFS-KW8'

Synonyms / alternative names
Acer saccharum AUTUMN FEST™

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

A fast-growing, upright cultivar suggested for use as a street tree by Dirr & Warren (2019). It develops a broad oval crown and exhibits orange to red autumn colour (Dirr & Warren 2019), turning earlier than typical Acer saccharum (Schmidt 2019). Introduced by J. Frank Schmidt & Son Co. (Schmidt 2019).


'Jocazam'

Synonyms / alternative names
Acer saccharum JOHNNYCAKE™

RHS Hardiness Rating: H7

USDA Hardiness Zone: 4

Of pyramidal form with leaves up to 30 cm wide, vigorous growth and vibrant orange-red autumn colour (Jacobson 1996). It was introduced in 1994–95 by Lake County Nursery, Ohio (Jacobson 1996).


'Legacy'

RHS Hardiness Rating: H6

USDA Hardiness Zone: 6-9

Selected by W. Wandell of Urbana, Illinois and introduced in 1981–82 by Moller Nursery, Oregon (van Gelderen, de Jong & Oterdoom 1994; Jacobson 1996). A vigorous grower, Acer saccharum ‘Legacy’ develops a heavily branched, rounded crown, ultimately attaining around 15 m (Jacobson 1996; Dirr & Warren 2019). Its leaves are glossy, tatter-resistant, and in autumn turn reddish in the northern United States, and orange to yellow in southern regions, where it is the most popular Acer saccharum cultivar, noted for its reliability (Dirr & Warren 2019). Its cold hardiness appears to be disputed, however, with Jacobson (1996, p. 58) noting it to be ‘exceptionally cold-hardy’, whereas Dirr & Warren (2019) suggest that it is less hardy than many other selections of the species. The hardiness indicators used here (USDA 6–9) reflect the opinions of the latter authors.


'Louisa Lad'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 4

Named and introduced by J.J.W.M. van den Oever, the Netherlands, in 1984, this is a fast growing form of broadly upright habit suited to use a street tree (van Gelderen, de Jong & Oterdoom 1994; van Gelderen & van Gelderen 1999). Noted for its vibrant yellow to orange-red autumn colours, which develop well in western European climates (van Gelderen & van Gelderen 1999). It was named after the Louisa Hof estate in the Netherlands, on which the den Oever Nurseries are based (van Gelderen, de Jong & Oterdoom 1994).


'Millane's Dwarf'

A slow growing, densely crowned selection of modest propoprtions, reportedly reaching 2.5 m tall in 15 years (Hatch 2021–2022). It was introduced by Theodore Klein of Kentucky in around 1980 (Hatch 2021–2022).

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

A densely crowned, slow growing selection of only modest proportions, reaching 2.5 m tall after 15 years (Hatch 2021–2022). It was introduced by Theodore Klein of Kentucky in around 1980 (Hatch 2021–2022).


'Morton'

Synonyms / alternative names
Acer saccharum CRESCENDO™

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

Introduced by The Morton Arboretum in the 1960s, this is a clone with darker leaves and some heat resistance (Dirr & Warren 2019). Its autumn colour is orange-red to bright red (Dirr & Warren 2019).


MOUNTAIN PARK™

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

An evenly branched selection resistant to mildew, and with strong orange to scarlet autumn colour, introduced by Moller Nursery, Oregon c. 1991–92 (Jacobson 1996). Jacobson lists only the trade designation (used here) and no alternative proper cultivar name has been traced.


'Newton Sentry'

Synonyms / alternative names
Acer saccharum 'Columnare'
Acer saccharum 'Erectum'
Acer saccharum 'Sentry' (in part)
Acer saccharum 'Monumentale' hort. non Temple

RHS Hardiness Rating: H7

USDA Hardiness Zone: 4-8

With a very columnar habit, this is the narrowest of all maples, and ‘as close as you can come to a living telephone pole’ (Dirr & Warren 2019, p. 128). It lacks a central leader and all main branches ascend vertically, with stubby lateral branches produced on the upright stems (Dathe 1983). A lack of low branches renders it unsuitable as a hedge and its leaves, which exhibit typical colour for the species, fall early (Dathe 1983; van Gelderen et al. 1994). Reported as rarely sold by Dirr & Warren (2019), the original tree was found in 1871 by A.H. Fewkes at Cafflin Grammar School, Massachusetts, where he was a student. Expansion of the school resulted in the tree being moved to Newton Cemetery in the 1870s (Dathe 1983). Measured at just over 12 m with a spread of 30 cm in 1954, the tree stood at over 15 m tall and 4 m wide in the 1990s (van Gelderen, de Jong & Oterdoom 1994).

This selection has historically been much confused with ‘Temple’s Upright’, though the confusion was finally resolved by Dathe (1983). The information that follows summarises his article, published in Arnoldia in 1983: Nurseryman F.L. Temple introduced ‘Newton Sentry’ (as A. saccharum columnare) via his Shady Hill Nurseries, Massachusetts in 1885–86, then two years later ‘Temple’s Upright’ (as A. saccharum monumentale). Though easily distinguished (‘Temple’s Upright’ has a broader habit and grows with a central leader, and without stubby lateral branches), the two names became confused and in an attempt to resolve the situation, Bernard Harkness, a Rochester, New York based taxonomist, proposed the names under which these are both known today in 1954. However, in his descriptions, he confused which of the two possessed stubby lateral branches, and further, an illustration accompanying his article (Baileya 2 (3): 99), shows ‘Newton Sentry’ to have a central leader, and ‘Temple’s Upright’ not. This error was perpetuated in several publications and on plant labels at the Arnold Arboretum, though long since corrected.


'October Sunrise'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 3

A cultivar of unknown origin with vibrant orange to red autumn colour (Hatch 2021–2022).


'Reba'

Synonyms / alternative names
Acer saccharum BELLE TOWER™

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

Introduced by J. Frank Schmidt & Son Co. (Hatch 2021–2022), a near-columnar selection made from material originating in Tennessee (Dirr & Warren 2019). Heat adapted, its autumn colour is yellow to orange (Dirr & Warren 2019).


'Sandborn'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

Acer saccharum ‘Sandborn’ is a narrow columnar selection that was named around 1958 (Jacobson 1996). It originated in Concord, New Hampshire, on land owned by a Mrs Sandborn (Jacobson 1996).


'Sandersville'

Synonyms / alternative names
Acer saccharum HARVEST MOON™

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

Introduced by J. Frank Schmidt & Son Co., Oregon in 2009 (Hatch 2021–2022) from material originating from the sandhills of Georgia (Dirr & Warren 2019). It has a broad oval crown and its autumn colours are consistently orange (Hatch 2021–2022). Dirr & Warren (2019) speculate that it may be a hybrid with Acer floridanum.


'Seneca Chief'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

Introduced by Schichtel Nursery, New York, in 1979, ‘Seneca Chief’ has a densely branched, narrow, oval crown (van Gelderen et al. 1994; Jacobson 1996). Its leaves turn yellow and orange in autumn (van Gelderen et al. 1994; Jacobson 1996).


'Shawnee'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

With a densely branched, ovoid form selected from a witch’s broom, ‘Shawnee’ was introduced by Theodore Klein of Kentucky, in 1980 (Hatch 2021–2022).


'Shawn's Pillar'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

A slow-growing selection, ‘Shawn’s Pillar’ has a similar form to ‘Newton Sentry’, but more compact (Hatch 2021–2022).


'Sisseton'

Synonyms / alternative names
Acer saccharum NORTHERN FLARE™

RHS Hardiness Rating: H7

USDA Hardiness Zone: 3

Introduced by J. Frank Schmidt & Son Co., Oregon, in 2011 (Hatch 2021–2022), it was selected from the western edge of the range of Acer saccharum in South Dakota (Dirr & Warren 2019). Described as ‘tough and reliable’ by (Dirr & Warren (2019, p. 128), it forms a broad crown with a strong central leader. Autumn colour is orange to red (Dirr & Warren 2019).


'Skybound'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 4

Of narrow upright habit, becoming broader with age, ‘Skybound’ was introduced by Synnestvedt Nursery, Illinois, in around 1988 (Hatch 2021–2022). It has yellow to orange autumn colour (Hatch 2021–2022).


'Sugar Cone'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

A compact, narrowly ovate and densely crowned selection described by Dirr & Warren (2019) as a ‘semi-dwarf’, ‘Sugar Cone’ was introduced around 2003 and has good orange to red autumn colour (Dirr and Warren 2019; Hatch 2021–2022).


'Summer Proof'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

A vigorous clone of spreading habit, as its name suggests ‘Summer Proof’ is heat tolerant, resisting windburn and sunburn (Jacobson 1996; Hatch 2021–2022).


'Sweet Shadow'

Common Names
Cutleaf Sugar Maple

Synonyms / alternative names
Acer saccharum 'Laciniatum'
Acer saccharum 'Sweet Shadow Cut Leaf'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

Introduced by Powell Valley Nursery, Oregon, in 1961–62 (Jacobson 1996), Acer saccharum ‘Sweet Shadow’ has an upright form becoming vase-shaped with age, with deeply dissected leaves that turn orange in autumn (Dirr & Warren 2019). It is favoured for its more fine-textured appearance compared with typical A. saccharum.


'Temple's Upright'

Synonyms / alternative names
Acer saccharum 'Monumentale'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 5

An upright clone first introduced in the 1880s by F.L. Temple of Shady Hill Nurseries, Cambridge, Massachusetts under the name ‘Monumentale’, but that name quickly became confused in the trade with another of Temple’s A. saccharum cultivars, ‘Columnare’ (now ‘Newton Sentry’) and so Temple’s ‘Monumentale’ was renamed ‘Temple’s Upright’ in 1954 (Jacobson 1996). It differs from ‘Newton Sentry’ in possessing a central leader and in the absence of short, stubby lateral branches (Dathe 1983). Further background on the source of the confusion between these selections is included in the account of ‘Newton Sentry’.


var. schneckii Rehder

Common Names
Schneck's Maple
Southern Hard Maple

Synonyms
Acer rugelii Pax
Acer saccharum subsp. ozarkense E. Murray
Acer saccharum var. rugelii (Pax) Rehder
Acer saccharum subsp. schneckii (Rehder) Desmarais

Differentiated from the typical variety by its shallowly lobed leaves with tips more rounded and margins of the central lobe slightly divergent. The lower leaf surface is pubescent throughout, with upright or tangled hairs (straight and appressed in var. saccharum) Flowers from April to June; fruit from June to September. (Grimshaw & Bayton 2009; Weakley & Southeastern Flora Team 2022).

Distribution

  • United States – Alabama, Georgia, Illinois, Indiana, Mississippi, Missouri, Ohio, Oklahoma, Pennsylvania

Taxonomic note As noted by Weakley and Southeastern Flora Team (2022), the taxonomic status (and distribution – see note below) of this variety is unclear, and it was recognised by these authors only provisionally in the hope that it would stimulate much needed research on the Acer saccharum complex. Var. rugelii, treated by Bean (1976) and accepted by van Gelderen et al. (1994) is treated in synonymy by Weakley and Southeastern Flora Team (2022), which this account follows.

The distribution given here follows (Weakley & Southeastern Flora Team 2022), which is far broader than that stated in New Trees (Grimshaw & Bayton 2009), though the former work notes a lack of clarity in some areas. Following this tentative interpretation, Acer saccharum var. schneckii overlaps with the typical variety though extends further south (Weakley & Southeastern Flora Team 2022). Where they overlap, they flower and fruit asynchronously, though are only weakly differentiated morphologically (see key to the group in main account for A. saccharum).

Given the uncertain status of this taxon, it is unsurprising that there are few plants in collections attributed to this variety. A plant at Arboretum Wespelaar, Belgium, sourced from Plantentuin Esveld and grown as var. schneckii, retains tangled hairs along along the veins on the fallen leaves (J. Ossaer pers. comm. 2022). van Gelderen et al. (1994) state that a plant so-named at Wageningen, The Netherlands, may not be accurately identified.


'Wright Brothers'

Synonyms / alternative names
Acer saccharum 'Moraine'

RHS Hardiness Rating: H7

USDA Hardiness Zone: 4

A selection of rapid growth, reportedly as much as twice the growth rate of typical Acer saccharum seedlings (Jacobson 1996). Introduced by Siebenthaler Nursery, Ohio in 1980, it has a broadly conical crown and strong yellow, orange and scarlet autumn colour which develops late in the season (Jacobson 1996; Dirr & Warren 2019).