Arbutus × andrachnoides Link

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Credits

Julian Sutton (2021)

Recommended citation
Sutton, J. (2021), 'Arbutus × andrachnoides' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/arbutus/arbutus-x-andrachnoides/). Accessed 2021-08-01.

Genus

Synonyms

  • Arbutus hybrida Ker-Gawler

Glossary

backcross
Cross between hybrid and one of the parent species.
glaucous
Grey-blue often from superficial layer of wax (bloom).
hybrid
Plant originating from the cross-fertilisation of genetically distinct individuals (e.g. two species or two subspecies).
included
(botanical) Contained within another part or organ.
morphology
The visible form of an organism.
pollination
Act of placing pollen on the stigma. Various agents may initiate pollination including animals and the wind.
serrate
With saw-like teeth at edge. serrulate Minutely serrate.

Credits

Julian Sutton (2021)

Recommended citation
Sutton, J. (2021), 'Arbutus × andrachnoides' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/arbutus/arbutus-x-andrachnoides/). Accessed 2021-08-01.

Variable hybrids intermediate between A. unedo and A. andrachne.

USDA Hardiness Zone 8-9

RHS Hardiness Rating H4

Awards AGM

Conservation status Least concern (LC)

This name covers all hybrids, whether of wild or garden origin, between A. unedo and A. andrachne. There is much variation within the limits set by the parental species (Bean 1976). As normally seen in gardens, it is a beautiful tree, tolerant of drought and thin chalk soils, with the peeling red-brown bark of A. andrachne, but hardier, faster growing, and without the ‘difficult’ reputation of A. menziesii. Of all Arbutus with peeling bark, this has to date been the leading choice for British gardeners. Of a famous specimen at Bodnant, N. Wales, Aberconway (1954) wrote ‘I know of no tree whose aspect alters more readily with the changing vagaries of light and shade, breeze and calm. When the evening sun lights upon its leaves and vividly illuminates its branches the whole tree is a most lovely sight’.

The parents hybridize in the wild, famously in Greece, but apparently wherever else they grow together (Tutin et al. 1972), even where A. andrachne is at the very edge of its range, as on a few Croatian islands (Bogdanović & Skendrović Babojelić 2018). They will also cross in cultivation, reputedly as early as 1800 on a London nursery (Bean 1976). Flowering at different times of year (andrachne in spring, unedo in autumn), the process must rely on rare out-of-season flowers, but their scarcity must serve to maximise the chance of pollination by the other species. The hybrids can be fertile (Bertsouklis & Papafotiou 2013), opening the way for introgressive hybridization with one or the other parent, and potentially making some individuals difficult to recognize as hybrids.

As seen in gardens, A. × andrachnoides has peeling red bark, somewhat toothed leaves which are glaucous beneath, flowers in either late autumn or spring, and relatively sparse orange-red fruits, smaller and with less warty surfaces than those of A. unedo (Bean 1976, Cullen et al. 2011, Huxley et al. 1992). Despite the potential for continuous variation, Bertsouklis & Papafotiou (2016) found that in two wild populations in Attica, Greece, individuals fell into three recognizable groups (two parents and the hybrid) based on morphology; molecular markers confirmed these groupings. In this Greek study, the hybrids had red bark which peeled in shorter strips than in andrachne; less basal branching than in unedo; leaves with serrate margins (approaching unedo) but leathery texture, shiny above (like andrachne), intermediate size and variable shape; fruits had the surface texture of andrachne but were intermediate in size and tasted sweet (like unedo); flowering time was with one or the other parent, depending on the individual. It is not clear how applicable these findings are to other populations.

Commonly available in British nurseries, The Tree Register (2021) records notable specimens from across the British Isles, though with fewer in Scotland and northern England. Among these are trees at: a private garden in Alvechurch, Worcestershire, laid out by Backhouse of York in 1891 (19.3 m × 443 cm, 2019); Battersea Park, London (a single trunk, 15 m × 295 cm, 2010); Cholmondeley Castle, Cheshire (single trunk, 14 m × 128 cm, 2014); and a private garden in Terenure, Co. Dublin, Ireland (4 trunks, 15 m × 357 cm, 2011). Elsewhere in non-Mediterranean Europe, this hybrid seems suited to the Low Countries and much of France: in Belgium, specimens are recorded at Arboretum Kalmthout, Arboretum Provinciaal Domein Bokrijk, and Arboretum Robert Lenoir, Rendeux (Plantcol 2021).

Arbutus × andrachnoides has never been close to the mainstream in North America. Although hardy on the Pacific seaboard and in parts of the southeast, it remains an uncommon botanic garden tree, scarcely ever offered by nurseries (Jacobson 1996). Attractive standards have been planted as a street tree at the JC Raulston Arboretum, NC (JC Raulston Arboretum 2021).

Several selections, supposedly with good foliage and large inflorescences were once named; variously styled as cultivar names or latinized epithets, they included “magnifica”, “photinaefolia” and “rollissoni” (Bean 1976), but seem to be unrecognized today, except in catalogues of names; some of these are also attributed to A. unedo in places. ‘Cinnamon Beauty’ appears to be no more significant. ‘Milleri’, a backcross between A. × andrachnoides and A. unedo f. rubra raised in the 19th century at John Miller’s Bristol Nursery, had large leaves and pink flowers (Elwes & Henry 1908), but might not still exist. Although itself a hybrid, Arbutus × andrachnoides has been implicated as a parent of the important cultivar ‘Marina’ (see A. × reyorum).