Meliosma beaniana Rehd. & Wils.

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Kindly sponsored by
Lady Diana Rowland

Credits

Owen Johnson (2022)

Recommended citation
Johnson, O. (2022), 'Meliosma beaniana' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/meliosma/meliosma-beaniana/). Accessed 2022-07-03.

Genus

Synonyms

  • Meliosma alba (Schltdl.) Walp., in part (sensu Beusekom)
  • Kingsboroughia alba Liebm., in part

Glossary

IUCN
World Conservation Union (formerly the International Union for the Conservation of Nature).
Least Concern
IUCN Red List conservation category: ‘does not qualify for Critically Endangered Endangered Vulnerable or Near Threatened. Widespread and abundant taxa are included in this category.’ ‘Lower Risk’ was formerly used and many tree species are still so-categorised in the Red List.
dbh
Diameter (of trunk) at breast height. Breast height is defined as 4.5 feet (1.37 m) above the ground.
herbarium
A collection of preserved plant specimens; also the building in which such specimens are housed.
monograph
Taxonomic account of a single genus or family.
pollen
Small grains that contain the male reproductive cells. Produced in the anther.
synonym
(syn.) (botanical) An alternative or former name for a taxon usually considered to be invalid (often given in brackets). Synonyms arise when a taxon has been described more than once (the prior name usually being the one accepted as correct) or if an article of the International Code of Botanical Nomenclature has been contravened requiring the publishing of a new name. Developments in taxonomic thought may be reflected in an increasing list of synonyms as generic or specific concepts change over time.

Credits

Owen Johnson (2022)

Recommended citation
Johnson, O. (2022), 'Meliosma beaniana' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/meliosma/meliosma-beaniana/). Accessed 2022-07-03.

A deciduous tree to 25 m, of rather upright habit. Bark pale grey-brown, with shallow, vertical, scaly ridges. Young twigs with rust-coloured woolly pubescence. Leaves 15–35 cm long, with (5–)9(–13) leaflets; petiolule of terminal leaflet with a distinct joint in it where two further leaflets do not develop; other petiolules 2 mm long. Leaflets ovate, pointed, 50–150 × 25–35 mm (increasing in size towards the leaf-tip), with 8–10 pairs of veins which curve inward, not reaching the margin; margin with tiny distant teeth, rarely entire; upper surface dull green, slightly roughened, both surfaces and petioles with a dense rusty pubescence at first; yellow tufts persisting under the vein axils. Flower-heads axillary, or clustered near the shoot-tips, expanding before the leaves; panicle spreading or drooping, 12–30 cm (including the 2–5 cm peduncle), branching usually twice and no more than 3 times; stems with rusty pubescence. Sepals 4. Petals pale yellow or cream. Drupe globose, 6–7 mm wide. (Guo & Brach 2007Bean 1981).

Distribution  Myanmar Mountains in the north of the country China Fujian, NW Guizhou, Hubei, Hunan, Jiangxi, Sichuan, N Yunnan, Zhejiang

Habitat Wet mountain forests

USDA Hardiness Zone 7

RHS Hardiness Rating H5

Conservation status Not evaluated (NE)

In flower Meliosma beaniana is one of the showiest of the genus, as the spreading or cascading panicles open just before the leaves in airy masses of tiny off-white blossom. In its native region it is often planted around temples and wayside shrines (Bean 1981), and it also provides timber for cabinet making (Guo & Brach 2007). The first westerner to see this tree was Ernest Wilson, who collected seed in Hubei in 1907 (W 154 and W 258) (Royal Botanic Garden Edinburgh 2022); in cultivation this seems likely to be a long-lived plant and four of Wilson’s original seedlings survive in UK gardens.

One of the most eccentric decisions made by T.H. van Beusekom in his 1971 monograph on the Asiatic Meliosma (van Beusekom 1971) was to sink this species in M. alba, a tree from southern Mexico which had first been described (as Millingtonia alba) by Diederich von Schlechtendal in 1842; Beusekom could observe no differences between flowers and foliage of the Asian tree and herbarium specimens of Mexican M. alba. In his 1988 Supplement to Trees and Shrubs Hardy in the British Isles, Desmond Clarke (Clarke 1988) adopted Beusekom’s then-fashionable nomenclature but baulked in this case, being obviously reluctant to relinquish one of the rather few plant names which commemorate that most erudite and gifted of horticultural writers. As of 2022, some authorities, including Flora of China (Guo & Brach 2007), continued to treat M. beaniana as a synonym of M. alba, and it is unclear whether or how far the IUCN’s assessment of M. alba as a species of Least Concern takes into account the Asian population; van Beusekom himself believed that the Chinese plant was an increasingly rare, relic tree (van Beusekom 1971).

The first major phylogenetic study of Meliosma and its allies was published by Tuo Yang et al. in 2018 (Yang et al. 2018), who were particularly interested in this case of possible synonymy. The results upheld van Beusekom’s assumption that M. alba and M. beaniana are indeed very close in evolutionary terms; they provide one of many examples of sister plants which have found themselves isolated by long-term climatic changes but have found no reason to alter their appearance. In this particular case the rate of random genetic drift appears to have been exceptionally slow, but this can be explained by the generation span of a long-lived tree and perhaps by the tendency of many Meliosma to reproduce apomictically.

A more surprising product of the work of Yang et. al. was to suggest that Meliosma alba and M. beaniana may be less closely related to the rest of Meliosma than the members of the South American genus Ophiocaryon are, even though M. alba (in Mexico) exhibits the trade-mark explosive pollen release mechanism of most Meliosma species, which is lacking in Ophiocaryon (Zúñiga 2015). One way of respecting the genetic isolation of M. alba and M. beaniana would be to resurrect for them the unpronounceable generic name Kingsboroughia (commemorating the New World ethnographer Viscount Kingsborough) which had been published, for the Mexican population, by Frederik Liebmann in 1850. However, the combination within Kingsboroughia for M. beaniana has not yet been made, and gardeners may well feel that the Chinese tree’s individuality has already been compromised by more than enough changes in name.

With its tall, rather upright habit and its flowers which are carried in spring just as the new growth expands, Meliosma beaniana is certainly a distinctive plant in the few UK collections where it is grown. It is hardy enough to have made a fine tree at the Royal Botanic Garden Edinburgh, 12 m tall in 2014 (Tree Register 2022). Another of Wilson’s originals was grown by Vicary Gibbs in his vast arboretum at Aldenham in Hertfordshire, and was moved to Borde Hill in West Sussex when that collection was dispersed following Gibbs’ death in 1932. It was big enough by this time to have flowered well the following spring (Bean 1981), and was ‘rediscovered’ 80 years later in the middle of one of the bramble patches in which Borde Hill excels, by which time it had reached 10 m (Tree Register 2022). A better tree, 19 m × 59 cm dbh, grows in the shelter of the Dell at Bodnant in north Wales. This is the largest Meliosma known in cultivation, though in 2005 – when the Dell tree was mislabelled as M. oldhamii – there was an unlabelled specimen 24 m tall in a little-visited corner of the estate, which has since been lost; with its leaves far out of reach it unfortunately could not be positively identified (Tree Register 2022). A fourth original, obtained from Kew in 1919, grows at Caerhays in Cornwall and was 8 m tall in 2016 (Tree Register 2008). Together, these gardens represent almost the full range of UK microclimates, to show that M. beaniana is tougher than its southerly origins might suggest. A 2016 planting at de Nieuwe Ooster crematorium in Amsterdam (de Nieuwe Ooster crematorium 2022) seems likelier to test the species’ hardiness to its limits.

Attempts to reintroduce Meliosma beaniana to Kew have failed (Edwards & Marshall 2019), but seedlings from one self-fertile tree in cultivation have recently been sold by Pan-Global Plants (N. Macer pers. comm. 2022). There seems to be no evidence for the cultivation of M. beaniana (or Mexican M. alba) in temperate North America.