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A deciduous tree up to 60 ft in height, young shoots not downy, becoming grey and slightly fissured the second year. Leaves five- or seven-lobed, 3 to 6 in. across, and rather more in length, the lobes ovate-triangular, ending in a long, narrow apex, the lowest pair spreading outwards; the base of the leaf is heart-shaped, the margins not toothed; the stalk has a milky sap, and both surfaces are green and glabrous except for tufts of hairs in the vein-axils beneath. Flowers appearing in April or early May with the first leaves, greenish yellow, in corymbose racemes 2 to 3 in. long. Fruit with glabrous wings, about 11⁄2 times as long as the nutlets, the pairs spreading almost horizontally or ascending; less commonly they are parallel and almost connivent (f. connivens (Nichols.) Rehd.); each key 3⁄4 to 11⁄4 in. long.
Native of Japan, Manchuria, N. and Central China, and Pacific Russia; introduced by Maries from Japan in 1881 under Thunberg’s name A. pictum, published in 1784. This cannot stand, since Thunberg had used it a year earlier for a plant that was not a maple at all but the member of the aralia family now known as Kalopanax pictus (Acanthopanax ricinifolium). Maximowicz’s name is in any case much to be preferred: the type of A. pictum was in fact a garden tree with variegated leaves (hence the epithet chosen) and had the wings of the fruit connivent, although this form is not common in the wild state of the species. The typical A. mono was introduced in 1901 by Wilson, when collecting in China for the Veitch nurseries, but had reached cultivation on the continent some years earlier by way of St Petersburg.
A. mono is a handsome tree, resembling A. cappadocicum (q.v. for the differentiative character), but is rarer in cultivation; most trees going under the name “A. pictum” are really A. cappadocicum. In the wild state, A. mono varies somewhat in the size, shape and indumentum of the leaf.
The first of the above synonyms represents Dr Murray’s original view. Subsequently (Kalmia, Vol. 8, p. 5), he submerged A. mono in A. truncatum and made the latter a subspecies of A. cappadocicum. However, de Jong considers A. truncatum and A. mono to be two distinct species.
A. mono is uncommon in cultivation, but there is a fine specimen at Hergest Croft, Herefordshire, measuring 82 × 73⁄4 ft at 3 ft (1985). Two examples at Kilmun, Argyll, planted 1935, measure 50 × 3 ft and 46 × 43⁄4 ft at 2 ft (1978). They were received under the Japanese name for the species – ‘Itaya-kaede’. In Eire there is a good specimen at Birr Castle, Co. Offaly, of 69 × 73⁄4 ft (1985).
A. mono was reintroduced to Kew in 1982 from Mount Pukhan, north-west of Seoul, South Korea (B.E. & C. 226).
A. fulvescens – The Borde Hill tree measures 34 × 41⁄4 ft (1981); there is another example at Arley Castle, Worcestershire. It is doubtful whether A. fulvescens can be maintained as a species distinct from A. mono.
† A. okamotoanum Nakai – A near ally of A. mono, differing chiefly, according to Fang, in its large fruits, with nutlets 5⁄8 in. wide, and wings up to 2 in. long. Native of Ullung-do (Dagelet Island) off the east coast of Korea.
A. ambiguum Dipp
A. mayrii Schwer
A. tenellum Pax