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A deciduous tree to 15 m in the wild. Bark dark green with pale stripes. Branchlets glabrous, purplish red, faintly striped white. Buds stipitate, oblong to ellipsoid, with two pairs of valvate scales. Leaves pentagonal, chartaceous, base cordate to subcordate, three- (rarely five-) lobed, 7–14 × 5–8 cm, central lobe ovate, triangular-ovate, apex caudate-acuminate, lateral lobes triangular-ovate, apex acuminate; margins double-serrulate, teeth adpressed, upper surface dark green, lower surface paler; petiole 4–7 cm long, green to red, grooved, pubescent or not; autumn colours yellow. Inflorescence terminal, racemose, pendulous, less than 10 flowered, ~4 cm long. Flowers yellowish green, 5-merous, pedicels slender, sepals oblong, ~0.3 cm long, petals obovate, ~3 cm long, stamens eight, inserted outside the nectar disc. Samaras 2.5–2.7 cm long, wings narrowly spreading to nearly horizontally so. Flowering May, after the leaves, fruiting October. (Fang 1939; Xu et al. 2008).
Distribution China Sichuan, Yunnan
Habitat Temperate mixed forests between 1800 and 2500 m
USDA Hardiness Zone 6-7
RHS Hardiness Rating H6
Conservation status Least concern (LC)
Representation of plants attributed to Acer laxiflorum in collections has increased somewhat since Bean (1976), thanks in part, to the successful SICH expeditions, which introduced greater diversity of a range of Chinese Acer taxa, over the course of the nine expeditions (Kirkham 2013). New material has not, however, resolved the taxonomic confusion around this taxon, of which Bean wrote, in relation to its relationship with Acer forrestii, as summarised in the account of that species. Suffice to say here that confusion between the two taxa remain, with at least as much material in collections not conforming to the description of one or the other, as that which does. While Xu et al. (2008) use flower number as a character to help distinguish between the two, as with other taxa in the section, this is proved by cultivated material to be a problematic character. Both taxa are treated as part of Acer pectinatum by van Gelderen, de Jong and Oterdoom (1994), though feel at least more comfortable as separate species rather than being included within that species, as treated by Xu et al. (2008). In cultivation, Acer pectinatum (sensu Xu et al. 2008) is easily separated from A. laxiflorum and its affinities by its bark, which soon turns brown with age (also see account for that species).
van Gelderen, de Jong and Oterdoom (1994) included four varieties within A. laxiflorum, all since reduced to synonymy by Xu et al. (2008). These were distinguished on minor variations of lobing and pubescence. Crucially, in relation to cultivated material, when assigning specimens to his earlier variety longilobum (now a synonym of A. pectinatum subsp. taronense), Rehder (1933) excluded W 4108, which he transferred to typical A. laxiflorum. However, this detail was seemingly overlooked by van Gelderen, de Jong and Oterdoom (1994) and hitherto not picked up by all who grow this collection, which may consequently be found growing as A. pectinatum subsp. taronense, rather than A. laxiflorum.
Originally introduced in 1908 by Wilson (Harris 2000), trees mentioned by Bean (1976) at Trewithen, Cornwall, are still alive and were in good health in May 2019. The SICH introductions include SICH 25, which grows strongly at the David C. Lam Asian Garden, University of British Columbia Botanical Garden, though it is otherwise absent from collections surveyed for SICH material by Charles Erskine in 2013 (Erskine, unpublished, 2013). SICH 0303 and 2114 grow at Quarryhill Botanical Garden, California, the latter also represented at RBG Kew and elsewhere. Specimens of SICH 2448 include two at Windsor Great Park, one of which forming a mutlstemmed plant in the Valley Gardens, with arching branches.
Regarding W 4108, of which repropagated material grows at Windsor and RBG Kew, Bean (1976 p. 207) states that ‘the leaves on the extension growths and young spurs are strongly three-lobed; on older, branched spurs they are less lobed but always strongly three-veined. The difference between this and the Trewithen trees is very striking, but it would appear to belong to A. laxiflorum as at present understood’. Variation of this sort is also a feature of other plants attributed to both A. laxiflorum and A. forrestii, further supporting the need for molecular work on the section.
For further confusion among cultivated plants, material introduced by a German nursery and apparently frequent in European collections in the 1990s in fact belonged to A. capillipes van Gelderen, de Jong and Oterdoom (1994). Whether this problem remains in parts of mainland Europe has not been traced, but it has not been observed in British or North American collections.