Acer japonicum

Classification System: APG IV

Superregnum: Eukaryota
Regnum: Plantae
Cladus: Angiosperms
Cladus: Eudicots
Cladus: Core eudicots
Cladus: Rosids
Cladus: Eurosids II
Ordo: Sapindales

Familia: Sapindaceae
Subfamilia: Hippocastanoideae
Tribus: Acereae
Genus: Acer
Species: Acer japonicum
Name

Acer japonicum Thunb.
References

in J. A. Murray, Syst. veg. ed. 14:911 (1784 May-Jun); Fl. Jap. 161 (1784 Aug)
USDA, ARS, Germplasm Resources Information Network. Acer japonicum in the Germplasm Resources Information Network (GRIN), U.S. Department of Agriculture Agricultural Research Service. Accessed: 08-Apr-12.

Vernacular names
čeština: Javor japonský
Deutsch: Japanischer Ahorn
dolnoserbski: Japański klon
English: Fullmoon Maple
español: Arce afelpado Japonés
suomi: Hokkaidonvaahtera
français: Érable du Japon
hornjoserbsce: Japanski klon
magyar: Vörösvirágú juhar
日本語: ハウチワカエデ
norsk nynorsk: Japanlønn
norsk: Japanlønn
polski: Klon japoński
русский: Клён японский

Acer japonicum, the Amur maple,[2] downy Japanese-maple[3] or fullmoon maple (Japanese: はうちは楓, romanized: hauchiwakaede), is a species of maple native to Japan, on Honshū, Hokkaidō, Kyūshū (Nagasaki Prefecture), and also southern Korea.[4]

Description

Acer japonicum is a small deciduous tree growing to 5–10 m (rarely 15 m) tall, with a trunk up to 40 cm in diameter. The bark is smooth on young trees, becoming rough and scaly on old trees. The shoots are slender, and thinly downy with whitish hairs. The leaves are rounded, 7–15 cm in diameter with 9–13 (rarely 7) serrate lobes incised to half or less of the diameter of the leaf; they are downy at first with white hairs, the hairs mostly lost by late summer except on the veins and the underside of the leaf; the petiole is 2–4 cm long and hairy. In autumn, the leaves turn bright orange to dark red. The flowers are 1 cm in diameter, dark purplish-red with five sepals and petals; they are produced 10–15 together in drooping corymbs in early spring as the leaves start to open. The fruit is a paired samara with the nutlets 7 mm in diameter with a 20–25 mm wing, hanging under the leaves.[4][5][6]
Cultivation

Acer japonicum is frequently cultivated as an ornamental plant in temperate regions of Europe, North America, and elsewhere, though much less commonly than A. palmatum. In cultivation, it is often only a shrubby tree with multiple trunks joining at ground-level.[5]

Its preferred growing conditions are similar to those of A. palmatum, but it is sometimes considered more tolerant of cold, especially compared to the more delicate cultivars of the latter.[5]

Numerous cultivars have been selected, some of which have their own common names (e.g. "grape-leaf maple" for A. japonicum 'Vitifolium').[7] Other popular cultivars are 'Aconitifolium'[8] ("downy Japanese maple") which has deeply incised leaves; and 'Green Cascade', with drooping to pendulous branches. All three cultivars have gained the Royal Horticultural Society’s Award of Garden Merit. Because of their variation from the wild species, some cultivars are difficult to assign to species, and they have often been mis-labeled as cultivars of the other related species; notably 'Aureum' has commonly been cited as a cultivar of A. japonicum, but is actually derived from A. shirasawanum.[5][6][9]

Cultivars of this maple are found in almost every maple collection including Esveld Aceretum (Boskoop, Netherlands) and the large Acer section of Arnold Arboretum (Boston, Massachusetts, USA). They are also common in more general collections of horticulture, such as Valley Gardens (Surrey, England).
Similar species

The closely related species Acer shirasawanum (Japanese, オオイタヤメイゲツ ooitayameigetsu) from southern Japan is sometimes included as a subspecies of A. japonicum.[5] It is distinct in its hairless shoots, and usually smaller leaves. Another related species, Acer sieboldianum (Japanese: コハウチワカエデ kohauchiwakaede), is best distinguished by its yellow (not red) flowers, and smooth bark even on old trees. It is more easily distinguished from Acer palmatum, as that species rarely has leaves with more than seven lobes.[6]
References

The Plant List, Acer japonicum Thunb.
USDA, NRCS (n.d.). "Acer japonicum". The PLANTS Database (plants.usda.gov). Greensboro, North Carolina: National Plant Data Team. Retrieved 6 January 2016.
BSBI List 2007 (xls). Botanical Society of Britain and Ireland. Archived from the original (xls) on 2015-06-26. Retrieved 2014-10-17.
Kanagawa Prefecture trees and shrubs: Acer japonicum Archived 2009-10-24 at WebCite (in Japanese; google translation). Archived 2009-10-24.
van Gelderen, C. J. & van Gelderen, D. M. (1999). Maples for Gardens: A Color Encyclopedia.
Rushforth, K. (1999). Trees of Britain and Europe. Collins ISBN 0-00-220013-9.
"RHS Plant Selector Acer japonicum 'Vitifolium' AGM / RHS Gardening". Apps.rhs.org.uk. Retrieved 2 March 2020.
"RHS Plant Selector Acer japonicum 'Aconitifolium' AGM / RHS Gardening". Apps.rhs.org.uk. Retrieved 2 March 2020.
Huxley, A., ed. (1992). New RHS Dictionary of Gardening. Macmillan ISBN 0-333-47494-5.