Photinia davidiana (Decaisne) Cardot (syn.: Stranvaesia davidiana Decaisne) (SE-As.) – A very rare but increasing, more or less persistent escape from cultivation (bird sown or garden throw-out?). Several young bushes are known since at least 2007 from the margin of coastal woodland (Koningsbos) in Knokke. In 2010 furthermore discovered in shrubland in Antwerpen-Linkeroever (foot of tree, obviously bird sown) and in 2011 in woodland near Aalter (ca. 8 young bushes). In the past years also observed in similar circumstances in Kortrijk and Mol (see here for an up-to-date overview of recent Belgian records: http://waarnemingen.be/soort/view/199878).
Similar records are also available from the British Isles (Palmer 1984, Clement & Foster 1994).
One of the more popular races in cultivation is cultivar ‘Redstar’ (Gardner & Knees 1995), a putative hybrid of Photinia davidiana and P. xfraseri. The existence of such hybrids further blurs the boundaries of Photinia and Stranvaesia and surely questions the reliability of their separation as advocated by some recent studies (e.g. Phipps 1990, Lingdi & Spongberg 2003 a, b). Some escapes from cultivation of garden throw-outs may represent this cultivar.
The Taiwanese endemic Photinia niitakayamensis Hayata is hardly distinguished from and better accepted as a synonym of P. davidiana (see Taylor 1988, Lingdi & Spongberg 2003 a, b).
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Selected literature:
Gardner M.F. & Knees S.G. (1995) Photinia. In: Cullen J. & al. (eds.), The European Garden Flora, vol. 4. Cambridge University Press, Cambridge: 424-426.
Lingdi L. & Spongberg S.A. (2003a) Photinia. In: Wu Z.Y. & Raven P.H. (eds.), Flora of China, vol. 9. Science Press, Beijing & Missouri Botanical Garden Press, St. Louis: 121-137. [available online at: http://flora.huh.harvard.edu/china/PDF/PDF09/Photinia.PDF]
Lingdi L. & Spongberg S.A. (2003b) Stranvaesia. In: Wu Z.Y. & Raven P.H. (eds.), Flora of China, vol. 9. Science Press, Beijing & Missouri Botanical Garden Press, St. Louis: 119-121. [available online at: http://flora.huh.harvard.edu/china/PDF/PDF09/Stranvaesia.PDF]
Phipps J. B., Robertson K.R., Smith P.G. & Rohrer J.R. (1990) A checklist of the subfamily Maloideae (Rosaceae). Can. J. Bot. 68: 2209-2269.
Ohashi H. & Iketani H. (1994) A new name for a Taiwanese Photinia (Rosaceae). J. Jap. Bot. 69(1): 22-23.
Palmer J.R. (1984) Stranvaesia davidiana Decne. – A future member of the British Flora? BSBI News 36: 27.
Taylor N.P. (1988) 109. Photinia niitakayamensis (Rosaceae). Kew Magazine 5(4): 148-151.