Cladrastis wilsonii Takeda

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Credits

Owen Johnson (2021)

Recommended citation
Johnson, O. (2021), 'Cladrastis wilsonii' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/cladrastis/cladrastis-wilsonii/). Accessed 2021-05-18.

Synonyms

  • Cladrastis lichuanensis Q.W. Yao & G.G. Tang

Glossary

IDS
International Dendrology Society sponsors of this book.

Credits

Owen Johnson (2021)

Recommended citation
Johnson, O. (2021), 'Cladrastis wilsonii' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/cladrastis/cladrastis-wilsonii/). Accessed 2021-05-18.

Tree to 16 m, often with a spreading habit from a short bole. Bark grey or grey-brown, thin and smooth, with a pattern of round lenticels. Shoots slender, pubescent at first. Buds concealed through summer within the swollen base of the leaf-stalk, which is also pubescent. Leaves with 8–11 leaflets, each 3.5–14 × 1.8–6.5 cm, with a broadly cuneate base and an acute tip, widest at or above halfway up; they are carried alternately on the rachis on petiolules 4–5 mm long, which are pubescent in early summer; leaflets are pale green or slightly greyish beneath with dense golden hairs under the veins. Inflorescence terminal or axillary, 10–28 cm long, drooping; flowers opening May-July (in China). Calyx campanulate, 7–8 mm, with triangular teeth, yellow-brown tomentose. Corolla white; flower c. 20 mm. Ovary densely sericeous. Fruit-pods oblong, flattened, 4.5–8 × 0.8–1 cm, beaked at the tip. Seeds 1–5, grey-brown, reniform, ripening August-September (in China). (Flora of China 2021).

Distribution  China Anhui, Fujian, Gansu, Guangxi, Guizhou, Henan, Hubei, Hunan, Jiangxi, Shaanxi, Shanxi, Sichuan, Yunnan, Zhejiang.

Habitat Hill forests at 1000–1500 m asl.

USDA Hardiness Zone 6

RHS Hardiness Rating H6

Conservation status Least concern (LC)

Differing from Cladrastis delavayi in its fewer and less markedly oblong leaflets, which are less silvery underneath, and in its flowers which are individually larger but are carried in smaller and more drooping heads, Cladrastis wilsonii was introduced to the west by E.H. Wilson in 1907 (W 1102). By this stage in his plant-hunting career, Wilson’s seed consignments were received by the Arnold Arboretum; one seedling was obtained by the Royal Botanic Gardens, Kew in 1910 (Bean 1976). This was propagated by grafting on the American C. kentukea but - possibly because of compatibility issues - all the scions at Kew are said to have died by the 1980s without ever flowering (Clarke 1988), though they did at least show a good yellow autumn colour (Bean 1976). Clarke also commented that W. 1102 was a field number, covering various collections both of C. wilsonii and C. delavayi, and suggested that some ‘C. wilsonii’ in cultivation might really be C. delavayi; certainly the foliage differences between the Kew trees and typical C. delavayi seemed less marked than is the case for typical C. wilsonii in the wild (Clarke 1988). Susyn Andrews, in her coverage of the genus for the IDS’ ‘Tree of the Year’ in 1996 (Andrews 1997), contradicted Clarke by indicating that a single tree from this source was still alive at Kew in 1996, and was clearly C. delavayi. A tree at the RHS Wisley Garden, also believed to be from W 1102, was nearing the end of its life in 2000 and was cut hard back in 2006 (Tree Register 2021). Before its final demise, Matt Pottage succeeded in raising grafts (N. Macer pers. comm.); scions from these have sometimes been available from PanGlobal Plants (Pan-Global Plants 2020) but the authenticity of this lineage has probably never been confirmed.

The true Cladrastis wilsonii was reintroduced to England in 1996, from seed distributed by Shanghai Botanic Garden (SBG 96/213); one planted by James Harris in the New Arboretum at Mallet Court in Somerset was a thriving young 3 m tree in 2017 (Tree Register 2021). In France the species is now sold by Pépinière Aoba (Pépinière Aoba 2021), perhaps from the same source. In the United States, any survivors from Wilson’s introduction to the Arnold Arboretum had been lost by 1977 (Robertson 1977), possibly for lack of hardiness in Massachusetts, and there seems to be no evidence of subsequent reintroductions.

Most of the trees from the forests where Cladrastis wilsonii grows wild make good garden plants in north-west Europe and flower regularly. With its elegant foliage and habit, typical of this genus, this rarity should probably be given a few more chances to prove its worth.