Acer sinopurpurascens W.C. Cheng

(Sect. Lithocarpa, Sect. Lithocarpa)

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New Trees

Tree 8–10 m, though often smaller in cultivation. Bark greyish brown, almost smooth. Branchlets green initially, later grey-brown. Leaves deciduous, deeply five-lobed or rarely three-lobed, upper surface dull green, lower surface pale green, both surfaces pilose along the veins when young, margins entire or rarely dentate, apex acute or acuminate; petiole 4–8.5 cm long, slender, pubescent when young, exudes milky sap when broken; autumn colour yellow. Inflorescence lateral, pendulous or corymbose racemes with three to seven flowers, dioecious. Flowers 5-merous; sepals (three to) five (to six), ~0.5 cm long though unequal in size, purplish red, petals five (absent in staminate flowers), same length as sepals, stamens eight, inserted inside nectar disc. Samaras 3–6 cm long, pale yellow, bristly, wings spreading obtusely. Flowering April, fruiting September (China). Van Gelderen et al. 1994, van Gelderen & van Gelderen 1999, Xu et al. 2008. Distribution CHINA: southern Anhui, northeast Hubei, northern Jiangxi, northwest Zhejiang. Habitat Mixed forest between 700 and 1000 m asl. USDA Hardiness Zone 5–6. Conservation status Not evaluated. Illustration NT69, NT110. Cross-reference K106.

Although an attractive and elegant tree that deserves widespread cultivation, Acer sinopurpurascens is extremely rare in horticulture due to difficulties in its propagation, possibilities for grafting being limited by the absence of related species with latex (van Gelderen & van Gelderen 1999). Neither is seed a useful alternative as it is a dioecious species and specimens are widely separated. A few arranged marriages might be useful. The red flowers, appearing early in the year and on young plants, are spectacular (le Hardÿ de Beaulieu 2003).

The male tree is at Arboretum Trompenburg, growing by the canal running through the garden. When observed in 2005 it was c.10 m tall (25 cm dbh) with two more or less equal main stems from a fork at 3.5 m. The branches are spreading and slightly pendulous, bearing the dark green, three-pointed leaves as a light canopy. This specimen was obtained from Dr Illa Martin from Germany in 1964, as part of a dispersal of stock following the death of her husband, but its ultimate origin is unknown (van Hoey Smith 2001). In England a female tree at the Valley Gardens is mentioned and illustrated by van Gelderen & van Gelderen (1999), but this specimen is not recorded by TROBI. That database does however record two further good specimens, a 5 m tree at Batsford Park, Gloucestershire in 2003, and a 7.3 m male individual at the Sir Harold Hillier Gardens in 2002. A few plants propagated from the Trompenburg specimen have been distributed by Esveld, but overall this is a good example of a case where a concerted conservation attempt is needed to propagate a rare and recalcitrant species. In Poland, a female tree derived from Shanghai Botanic Garden seed has been hardy since 1981 at Rogów and has reached over 7 m – but again, being a solitary specimen, it does not set viable seed (Tumilowicz 2002). The species appears to be unknown in North American collections, but its hardiness should be useful there.

‘It is a truth universally acknowledged …’ This male Acer sinopurpurascens at Arboretum Trompenburg is certainly in need of a wife (see p. 110). It is easy to forget how attractive the flowers of maples can be. Image J.R.P. van Hoey Smith.

The solitary female specimen of Acer sinopurpurascens at Rogów never sets viable fruit. Image P. Banaszczak.

Genus

Acer

Other species in the genus