Cladrastis wilsonii Takeda — Wilson yellowwood

Introduction

Wilson yellowwood (Cladrastis wilsonii) is a deciduous tree of central and southern Chinese hill forests, typically occurring at about 1000–1500 m. Trees can reach approximately 16 m. The leaves usually carry 8–11 ovate to oblong-ovate leaflets, and drooping terminal or axillary panicles of white flowers open from May through July. Its mature legumes are narrow, flattened, beaked, and unwinged (Flora of China Editorial Committee 2010).

The species resembles Japanese C. shikokiana more closely than it does the narrow-leaved C. delavayi. Typical C. wilsonii has broader leaflets and greenish to yellow-brown rather than strongly rusty inflorescence pubescence. Available phylogenetic sampling has suggested an association between C. wilsonii and C. shikokiana, but support has not been strong enough to formalize that relationship as an infrageneric group (Duan et al. 2019).

Cladrastis lichuanensis, described from central China in 1988, is included in C. wilsonii by current global taxonomy. Its distinguishing features fall within a broader morphological and ecological concept of Wilson yellowwood rather than supporting a separate accepted species (Duan et al. 2019; Royal Botanic Gardens, Kew 2026).

Horticultural and Agricultural Uses

The most important horticultural fact about Wilson yellowwood is the uncertainty surrounding many cultivated plants bearing its name. Trees were introduced to Western collections during the twentieth century, but later scrutiny has suggested that a substantial proportion were misidentified, often representing another yellowwood or occasionally another allied legume. Authentic C. wilsonii may therefore be much rarer in cultivation than garden records imply (Johnson 2023).

For living collections, correct identity is more important than accumulating additional anonymous specimens. Wild collection numbers, provenance records, voucher specimens, and diagnostic comparison with C. delavayi and C. shikokiana are particularly valuable. Genuine material should be maintained and propagated as documented germplasm rather than relying on a horticultural name alone.

Conservation Concerns

Wilson yellowwood is assessed as Least Concern and occupies a broad area of central and southern China. Current information does not indicate a global extinction risk comparable with that of many narrow endemic trees (Royal Botanic Gardens, Kew 2026).

The cultivated identification problem nevertheless matters for ex situ conservation. A collection labeled C. wilsonii contributes little to representation of the species if its identity is uncertain. Verified wild-origin material from multiple parts of the native range would provide a much stronger conservation resource and would also enable denser phylogenetic sampling of the East Asian yellowwoods.

Additional Information

Plants of the World Online (opens in a new tab): Accepted taxonomy, Chinese distribution, conservation status, and synonymy of C. lichuanensis.
Flora of China (opens in a new tab): Detailed morphology, habitat, flowering and fruiting phenology, and regional distribution.
Trees and Shrubs Online (opens in a new tab): Horticultural history and detailed discussion of probable misidentification in Western collections.
iNaturalist (opens in a new tab): Species page with a small observation base; identifications should be treated cautiously given the genus’s known cultivation problems.

References and Further Reading

Duan L, Harris AJ, Ye W, Deng S-W, Song Z-Q, Chen H-F, Wen J (2019) Untangling the taxonomy of the Cladrastis clade (Leguminosae: Papilionoideae) by integrating phylogenetics and ecological evidence. Taxon 68(6): 1189–1203. DOI 10.1002/tax.12155 (opens in a new tab).

Flora of China Editorial Committee (2010) Cladrastis wilsonii. In: Wu ZY, Raven PH, Hong DY (eds) Flora of China, Vol. 10. Science Press, Beijing & Missouri Botanical Garden Press, St. Louis.

Johnson O (2023) Cladrastis wilsonii. Trees and Shrubs Online.

Royal Botanic Gardens, Kew (2026) Cladrastis wilsonii Takeda. Plants of the World Online.