Cotoneaster boisianus
Cotoneaster boisianus G. Klotz, Wiss. Z. Friedrich-Schiller Univ. Jena, Math.-Naturwiss. 21: 987, 1972.
Section Acutifolii, series Bullati
Origin: China (Sichuan).
Presence in western Europe: Naturalized in Great Britain (Stace 2010).
Cultivation in Belgium and the Netherlands: unknown; not separated from Cotoneaster bullatus by De Koning & al. (2000).
Comparative taxonomy: Species included in a broadly circumscribed Cotoneaster bullatus by Dickoré & Kasperek (2010; as a merely small-leaved and few-flowered form). Lingdi & Brach (2003) subsume this species under Cotoneaster bullatus (as var. floribundus (Stapf) L.T. Lu & A.R. Brach) (Lu & Brach 2002). According to Fryer & Hylmö (2009) this combination has been erroneously applied for Cotoneaster ignescens Fryer et Hylmö.
Illustrations: Stace (2010).
Cotoneaster boisianus is a lovely shrub, especially in autumn when it is laden with colourful fruit. Yet, it seems to be rare in cultivation in Belgium. It was formerly planted at a (now derelict) industrial plant of Bekaert in Zwevegem. In 2011 its escape was detected (scattered saplings in cracks of pavement, foot of walls, scrub, etc.). Some young, non-flowering shrubs recorded on the nearby calcareous slopes of the canal Kortrijk-Bossuit (Vaarttaluds) might also pertain to this species (comm. D. Derdeyn).
Although not accepted by most recent authors Cotoneaster boisianus is readily distinguished from C. bullatus and related species. Dickoré & Kasperek (2010) emphasize on quantitative (indeed very plastid) characters for its separation. However, fruit colour seems to be a better diacritic feature: fruits of Cotoneaster boisianus are of a bright orange to orange-red colour (like in C. ignescens and C. sikangensis Flinck & B. Hylmö; see Fryer & Hylmö 2009) while they are dullish dark red in C. bullatus and C. rehderi.
According to Lingdi & Brach (2003) Cotoneaster boisianus is an invalid name because Klotz (1972) cited two specimens from different gatherings as types.
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Literature
De Koning J., Van den Broek J.W., Van de Laar H.J. & Fortgens G. (2000) Nederlandse dendrologie (13e druk). H. Veenman & zonen, Ede: 585 p.
Dickoré W.B. & Kasperek G. (2010) Species of Cotoneaster (Rosaceae, Maloideae) indigenous to, naturalising or commonly cultivated in Central Europe. Willdenowia 40: 13-45 [available online at: http://user.uni-frankfurt.de/~kasperek/papers/dickore_kasperek_2010.pdf].
Fryer J. & Hylmö B. (2009) Cotoneasters. A comprehensive guide to shrubs for flowers, fruit, and foliage. Timber Press, Portland-London: 344 p.
Klotz G. (1972) Neue oder kritische Cotoneaster-Arten. 7. Wiss. Z. Friedrich-Schiller Univ. Jena, Math.-Naturwiss. 21: 979-1021.
Lingdi L. & Brach A.R. (2003) Cotoneaster. In: Wu Z.Y. & Raven P.H. (eds.), Flora of China, vol. 9. Science Press, Beijing & Missouri Botanical Garden Press, St. Louis: 85-108 [available online at: http://flora.huh.harvard.edu/china/PDF/PDF09/Cotoneaster.PDF].
Lu L.T. & Brach A.R. (2002) New combinations in Chinese Cotoneaster (Rosaceae). Novon 12(4): 495-496 [available online at: http://flora.huh.harvard.edu/china/novon/novo-12-4-495.pdf].
Stace C. (2010) New Flora of the British Isles, 3th ed.: XXXII + 1232 p. Cambridge University Press.