Acer circinatum Pursh

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Credits

Dan Crowley (2024)

Recommended citation
Crowley, D. (2024), 'Acer circinatum' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/acer/acer-circinatum/). Accessed 2024-06-18.

Genus

Common Names

  • Vine Maple

Other taxa in genus

Glossary

section
(sect.) Subdivision of a genus.
bud
Immature shoot protected by scales that develops into leaves and/or flowers.

Credits

Dan Crowley (2024)

Recommended citation
Crowley, D. (2024), 'Acer circinatum' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/acer/acer-circinatum/). Accessed 2024-06-18.

A many-stemmed shrub or small tree to 10 m. Bark brown, shallowly grooved. Branchlets green, sometimes tinged red, becoming brown with age, soon glabrous, sometimes somewhat sticky. Buds shiny red, fringed with white hairs, terminal bud absent. Leaves deciduous, orbicular in outline, base cordate, 5–13 cm across, palmately seven-lobed to nine-lobed to half-way to the base; the upper surface pubescent at least along the veins, the lower surface pubescent throughout, both surfaces becoming glabrous, margins serrate or double serrate, lobe apex acute; petiole ~4 cm long; autumn colours scarlet to yellow. Inflorescence corymbose. Flowers 0.6–0.9cm across, 5-merous, staminate or hermaphrodite; sepals red to purple, petals white, inserted in the middle of the disc. Samaras 2–5 cm long, wings broadly spreading. Nutlets ribbed. Flowering April and May, fruiting September to October. (van Gelderen, de Jong & Oterdoom 1994; Brayshaw 1996; Pojar & Mackinnon 2014).

Distribution  Canada British Columbia United States California, Oregon, Washington

Habitat Moist to wet areas, in forest understorey where light reaches the forest floor, and sometimes in open areas. Often forming suckering thickets covered with epiphytes. Occuring at low to mid elevations up to 2000 m asl.

USDA Hardiness Zone 4

RHS Hardiness Rating H6

Awards Award of Garden Merit

Conservation status Least concern (LC)

The sole member of Section Palmata Series Palmata native to North America, Acer circinatum is, along with A. macrophyllum, one of two maples introduced to Britain by David Douglas in 1826 (Bean 1976; Harris 1991). Both species were noted by Menzies in 1792 and collected by Lewis and Clark in 1804–5, though arrived courtesy of Douglas more than 20 years later (Harris 1991).

In the wild, Acer circinatum predominantly grows in understorey shade, where it develops an unbranched, vine-like habit, from which it takes its common name. Reproducing by means of basal sprouts, root layers and via seed (O’ Dea 2009), it is capable of forming more or less impenetrable thickets (Bean 1976), though when in the open it takes on a more typically shrubby, upright form (Justice, in prep). The species favours cooler, moist conditions, and when these prevail is suitable for both full sun or deep shade (Dirr & Warren 2019). It is also noted as drought tolerant (Dirr & Warren 2019), though this applies only when grown in shade (Justice, in prep). An extensive mass, probably a conglomeration of several original plants, grows in dappled shade on a steep, north-facing hillside at Winkworth Arboretum, Surrey, UK, on sandy soils prone to drying out, yet appears not to have suffered as a result of recent summer droughts and heatwaves (T. Christian pers. comm. 2024).

The species is grown in gardens largely for its strong autumn colour, though more often within its native range than elsewhere in our area, where its closest relatives including Acer japonicum and its east Asian affinities dominate. Vine Maple is equally well-suited to smaller gardens, with its purple-sepaled, white-petaled flowers accompanied by conspicuous, expanded inner bud scales providing spring interest. Plants sold are predominantly from seed-raised stock, though its cultivars are becoming more common. Dirr & Warren (2019) consider it a species with great potential: it shows more resilience to drought and verticillium wilt than Acer palmatum; selections made from the limits of its native range would see A. circinatum realise more of its horticultural potential.

Acer circinatum most resembles A. japonicum, with which it is easily mistaken. It can be distinguished by its smaller leaves, usually with fewer lobes (Vine Maple leaves are never 11-lobed, as in A. japonicum), and its shoots remain green and glossy for longer than those of A. japonicum, and are also often sticky. The two species hybridise in cultivation and can be used as rootstocks for one another as well as in combination with A. palmatum (van Gelderen et al. 1994). According to van Gelderen et al. (1994) A. circinatum grafted onto A. palmatum will produce a stronger plant than one grafted onto a rootstock of its own species. Hybrids with A. palmatum, A. shirasawanum and A. japonicum are reported from collections, and will be covered separately here in due course.

Wild-origin examples of the species are present in many collections in our area, including from recent introductions. Material collected by Ben Stormes (under BJS 2016–0051) grows at the University of British Columbia Botanical Garden, gathered from elswhere in British Columbia in the Fraser Valley Regional District. Recently planted Californian material grows at Westonbirt, collected in 2015 under COWS 003 from Quinault National Forest by staff from Bedgebury, Westonbirt and Oxford University. In the past few years staff from the Royal Botanic Garden Edinburgh have sampled the species in British Columbia and Oregon, with material from multiple provenances establishing at Edinburgh and at Benmore Botanic Garden, Argyll as well as at Howick, Northumberland, and elsewhere (Royal Botanic Garden Edinburgh 2024).


'Baby Buttons'

USDA Hardiness Zone: 5

Introduced by Buchholz Nursery, a round, small-leaved dwarf that originated as a witches’ broom, attaining little over half a metre in height and width in 10 years (Buchholz & Buchholz Nursery 2019).


'Burgundy Jewel'

USDA Hardiness Zone: 5

A selection of small stature with purple red leaves which hold their colour throughout the season, particularly in full sun, before turning orange and red in autumn (Buchholz & Buchholz Nursery 2019).


'Del's Dwarf'

USDA Hardiness Zone: 5

A dwarf clone introduced by Delbert L. Loucks of Eugene, Oregon, attaining little more than 1 m tall and wide in 20 years (Hatch 2021–2022). It has bronze new growth that turns green in summer, then yellow, red or orange in autumn (Hatch 2021–2022).


'Elegant'

USDA Hardiness Zone: 5

A clone selected by Hubert Rhodes in Skagit Valley, British Columbia, around 1954, and named later at the Dominion Arboretum, Ottawa (Jacobson 1996). It has leaves that are somewhat more incised and smaller than is typical for the species (Jacobson 1996).


'Glen Del'

USDA Hardiness Zone: 5

Selected at Del Lane’s County Nursery, Eugene, Oregon, in 1976, and introduced in 1982, ‘Glen Del’ has a compact, narrow, upright habit, with deeply cut, five-lobed leaves (Jacobson 1996). It was named after nurserymen Glen Handy and Delbert L. Loucks (Jacobson 1996).


'Hidden Valley'

USDA Hardiness Zone: 5

A selection with a shrubby habit, carrying bright green leaves that turn pink or red in autumn, introduced by Miyama Asian Maple Nursery, California (Hatch 2021–2022).


'HSI2'

Common Names
Upright Vine Maple

Synonyms / alternative names
Acer circinatum THREE CHEERS™

USDA Hardiness Zone: 5-8

A strongly upright cultivar, growing twice as tall as it does wide (Dirr & Warren 2019). Selected by Heritage Seedlings, Oregon (Heritage Seedlings & Liners 2021), its narrow habit lends itself to use in small gardens, and it is further suggested for use as a small street tree in the Pacific Northwest (Dirr & Warren 2019).


'JFS-Purple'

Synonyms / alternative names
Acer circinatum PACIFIC PURPLE™

USDA Hardiness Zone: 6

More compact than typical for the species, with fresh foliage tinted bronze, becoming purple before turning orange and red in autumn (Dirr & Warren 2019). Discovered by J. Frank Schmidt III, and introduced by J. Frank Schmidt & Son Co. (Schmidt 2019).


'Little Gem'

A selection made from a witches’ broom discovered by Alleyne Cook in Stanley Park, Vancouver (Hatch 2021–2022). Its half-size leaves are green in summer, turning orange or red in autumn, often to good effect (Hatch 2021–2022).


'Lyn'

USDA Hardiness Zone: 4

Grown from seed collected on Mount Hood, Oregon by Greg Morgenson of North Dakota, and named for his wife (Hatch 2021–2022). Considered hardier than many other selections, it reaches nearly 5 m tall with a broadly upright habit and was introduced by Iseli Nursery of Boring, Oregon (Hatch 2021–2022).


'Monroe'

USDA Hardiness Zone: 5

A cut-leaved clone discovered by Dr Warner Monroe of Portland, Oregon, along the Mackenzie River around 65 miles east of Eugene (van Gelderen, de Jong & Oterdoom 1994; Jacobson 1996). Monroe layered a plant where the original was found, taking the resulting plant home in 1965 (van Gelderen, de Jong & Oterdoom 1994). A second layer was acquired by J.D. Vertrees in 1970, who then began propagating the plant via grafting onto Acer palmatum (van Gelderen, de Jong & Oterdoom 1994) and the selection was introduced commercially in 1977 (Jacobson 1996). It is now cultivated on both sides of the Atlantic. Individuals develop a rounded crown with somewhat weeping stems, and are usually wider than tall and rarely more than 3 m in height after 25 years (Justice, in prep.). Foliage is a dull green, finely sharp-toothed, though not particularly sun-tolerant (Justice, in prep.), and also suceptible to mildew (van Gelderen, de Jong & Oterdoom 1994)


'Pacific Fire'

USDA Hardiness Zone: 5

A selection noted for its coral-red stems which are at their best in winter. New growth is vigorous, though plants need full sun to develop best (Dirr & Warren 2019). As for other maples with vivid young shoots such as selections of Acer tegmentosum, Dirr & Warren (2019) advocate cutting back each year to gain the best effect. In summer the foliage is lime green, turning yellow in autumn (Dirr & Warren 2019).


'Pacific Sprite'

A dwarf clone attaining 1.3 m in 10 years (Hatch 2021–2022). Its leaves are somewhat crinkly, darker green than most, and turn orange, yellow or red in autumn (Hatch 2021–2022).


'Si Yama'

USDA Hardiness Zone: 5

A small, densely branched plant speculated to have been derived from a witch’s broom by van Gelderen & van Gelderen (1999). Its leaves are up to 5 cm across, and it is noted as appropriate for bonsai (van Gelderen & van Gelderen 1999).


'Sunglow'

A compact clone attaining around 1 m in ten years, with golden yellow spring foliage, tinted orange or pink if sited in full sun, though dull if grown in shade. In autumn the leaves turn red and purple. Discovered by Fred McMullen of Portland, Oregon and introduced commercially by Buchholz & Buchholz Nursery (Hatch 2021–2022).


'Sunny Sister'

USDA Hardiness Zone: 5

Of somewhat smaller stature than typical for the species, this was selected for its pale-tinted spring foliage, which turns light green in summer (Dirr & Warren 2019). Autumn colour is yellow to orange (Dirr & Warren 2019). Introduced by Talon Buchholz, it is a sister seedling to ‘Sunglow’.


'Victoria'

USDA Hardiness Zone: 5

A cultivar that arose as a chance seedling at the Von Gimborn Arboretum, The Netherlands, and named by former director and acerologist Piet de Jong and introduced commercially by Plantentuin Esveld (van Gelderen & van Gelderen 1999). van Gelderen and van Gelderen (1999) describe it as shrubby, though the photo accompanying the description shows a plant that is distinctly tree-like.