Acer tschonoskii Maxim.

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Credits

D. Crowley (2019)

Recommended citation
'Acer tschonoskii' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/acer/acer-tschonoskii/). Accessed 2020-01-24.

Genus

Infraspecifics

Other species in genus

Glossary

strobilus
Cone. Used here to indicate male pollen-producing structure in conifers which may or may not be cone-shaped.
acuminate
Narrowing gradually to a point.
caudate
With a long tail-like appendage.
section
(sect.) Subdivision of a genus.
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.

References

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Credits

D. Crowley (2019)

Recommended citation
'Acer tschonoskii' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/acer/acer-tschonoskii/). Accessed 2020-01-24.

A deciduous shrub or tree 10–13 m in the wild. Bark grey-brown. Branchlets reddish brown, inconspicuously striped, glabrous. Buds stipitate, ovate-lanceolate, with two pairs of valvate scales. Leaves triangular-ovate, 5–10 × 7–11 cm, base cordate, palmately five-lobed, upper surface dark green, lower surface paler, often with rusty pubescence in secondary vein axils and along secondary veins, margins sharply doubly serrate, lobes ovate with apex acuminate to caudately acuminate; petiole 3–5 cm long, reddish, glabrous or pubescent and slightly grooved; autumn colour yellow to red. Inflorescence axillary or terminal, racemose, erect, ~10 flowered, 2–5 cm long. Flowers yellowish green, 5-merous, usually androdioecious; pedicels 1–1.5 cm long, sepals narrowly oblong 0.4–0.5 cm long, petals obovate-oblong, slightly shorter than, or as long as, sepals, stamens eight, inserted outside the nectar disc. Samaras 1.4–2.3 cm long, wings spreading obtusely. Flowering April to July (Japan), fruiting in October. (Ogata 1999; van Gelderen and van Gelderen 1999). 

USDA Hardiness Zone 5

RHS Hardiness Rating H5

Conservation status Least concern (LC)

One of 7 Japanese members of section Macrantha, Acer tschonoskii is somewhat unique in that its flowers are held erect, whereas those of the rest of the section are pendulous. Its bark is also less ‘snake-barked’, turning brown quickly and recalling that of A. pectinatum and some of its affinities, though these are not easily confused. Morphologically, A. tschonoskii is closest to A. komarovii and A. micranthum. Aside from its floral differences, it can be separated from both by its shorter terminal leaf lobes (leaf blade not wider than long) while its leaves are also larger in outline than A. micranthum.

Introduced to Britain in 1902 (Bean 1976) and North America 10 years prior (Rehder 1940), the species is largely restricted to specialist collections, though is not entirely without horticultural merit, turning satisfactory shades of yellow to red in autumn. The UK and Ireland Champion grows at Westonbirt, The National Arboretum, UK. Measuring 8 m tall in 2002 (TROBI 2019) and as least as wide as it is tall, it enjoys a sheltered location on deep sandy soil.

BBJMT 291, a collection made from Gifu Prefecture, Honshu (BBJMT 291), as var. australe is referable to Acer micranthum. True var. australe has flowers with sepals as long as petals, as opposed to petals longer than sepals found in the typical variety, smaller fruits and caudate-acuminate leaf lobes (de Jong 2019).


var. rubripes Komar

A native of N. Korea and N. China, differing from the type in the longer, more tapered lobes, the reddish leaf-stalks and young growth, and the more spreading wings of the fruit.

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