Acer pseudosieboldianum (Pax) Kom.

(Sect. Palmata, Sect. Palmata)

Common names

Keijo Maple, Korean Maple

Synonyms

A. microsieboldianum Nakai

Article sources

New Trees

Shrub or tree 8–10 m; crown rather open, often wider than tall. Branchlets sticky, long and slender with a whitish bloom. Leaves deciduous, papery, 10–15 cm wide, palmately 9- to 11-lobed, divided to half or two-thirds of the length, upper surface dark green, lower surface densely white pubescent, margins double-serrate, apex acuminate; petiole 3.5–4 cm long, densely pubescent when young; autumn colour yellow, orange or red. Inflorescence terminal, corymbose, pubescent. Flowers 5-merous, staminate or hermaphrodite; sepals lanceolate, reddish purple, petals white to cream, obovate, stamens eight. Samaras ~3 cm long, purplish yellow, wings strongly veined, spreading obtusely. Flowering May to June, fruiting September to October (China). Van Gelderen et al. 1994, van Gelderen & van Gelderen 1999, Xu et al. 2008. Distribution CHINA: Heilongjiang, southeast Jilin, eastern Liaoning; NORTH KOREA; RUSSIAN FEDERATION. Habitat Forests between 700 and 900 m asl. USDA Hardiness Zone 4–5. Conservation status Not evaluated. Illustration NT101. Cross-reference B206, K99. Taxonomic note A number of segregates were named by Nakai but are disregarded by van Gelderen et al. (1994); they occasionally appear in catalogues.

Despite being widely grown in maple collections throughout our area, Acer pseudo sieboldianum is rather overshadowed by its close relatives A. japonicum and A. palmatum and other members of series Palmata, which surpass it in foliage qualities, although not in hardiness. Dirr (1998) evaluates A. palmatum as suitable for Zones 5 and 6–8, but recommends A. pseudosieboldianum as a substitute in Zones 4–5, as being better able to tolerate low winter temperatures. This is borne out by experi ence at Rogów in Poland (Zone 6), where it flourishes and is hardier than both A. palmatum and A. japonicum (Tumilowicz 2002, Banaszczak 2007). The trees there, planted in 1974, are now reaching 8–9 m tall (P. Banaszczak, pers. comm. 2007).

Acer pseudosieboldianum subsp. pseudosieboldianum has leaves that are rounded, with short divisions, and thus lack the elegance associated with the Japanese maples. It was not recommended by van Gelderen et al. (1994) on account of a poor, ‘floppy and loose’ shape, and the habit of retaining dull brown leaves on the twigs for some time before they fall. This, however, contrasts with travellers’ descriptions of it (for example, E.H. Wilson, quoted in Bean 1976a; Flanagan & Kirkham 2005) as a brilliant autumn feature of its native forests, with yellow to scarlet colours – and the persistence of the leaves is seen by others as an advantage! Although its date of introduction is cited as 1903 (Krüssmann 1984, Johnson 2003), the details seem to be obscure. The largest specimen in the United Kingdom is in the Bute Park Arboretum, Cardiff, where it was 11 m tall in 2005 (TROBI).

Acer pseudosieboldianum subsp. pseudosieboldianum is a good choice for those seeking striking autumnal colour in areas too cold for A. palma-tum. Image P. Banaszczak.

Genus

Acer

Other species in the genus