Cotoneaster lacteus
Cotoneaster lacteus W.W. Smith, Not. Roy. Gard. Edinburgh 10: 23, 1917.
Synonyms: C. oligocarpus C.K. Schneider, C. smithii G. Klotz
Section Densiflori, series Pannosi
Origin: southwestern China.
Presence in western Europe: Naturalized in France (Verloove 2007; see also Farille & al. 2010), Great Britain (Stace 2010), Italy (Celesti-Grapow & al. 2009; sub Cotoneaster coriaceus), Spain (Pyke 2008; sub C. coriaceus).
Cultivation in Belgium and the Netherlands: “rare” and “frost sensitive” (De Koning & van den Broek 2009).
Comparative taxonomy: Some authors accept this species as a synonym of Cotoneaster coriaceus Franch., which is an earlier name (see for instance Lingdi & Brach 2003, Dickoré & Kasperek (2010). According to Klotz (1996) the typus of W.W. Smith’s Cotoneaster lacteus does not fully correspond with his description. Therefore, he described a new species, Cotoneaster smithii. Farille & al. (2010) also follow this taxonomy.
Illustrations: Roloff & Bärtels (2006; sub Cotoneaster smithii), De Koning & van den Broek (2009), Fryer & Hylmö (2009), Stace (2010). See also: http://www.ukwildflowers.com/Web_pages/cotoneaster_lacteus_late_cotoneaster.htm.
Cotoneaster lacteus is readily distinguished by its evergreen, coriaceous leaves that are yellowish tomentose beneath, obovate and usually rounded at apex and its multi-flowered inflorescences with white, spreading petals. From the related species that have been recorded in the wild in Belgium it is somehow reminiscent of Cotoneaster salicifolius but its leaves are much wider (obovate to broadly elliptic vs. lanceolate) and usually rounded to obtuse at apex (vs. acute to acuminate).
Cotoneaster lacteus is rather rare in cultivation in Belgium and perhaps not fully hardy (De Koning & van den Broek 2009). It has been recorded twice in the wild so far: a single young shrub grows on the brick quay wall of Achtervisserij in the city center of Gent since 2010. In the same year furthermore discovered on a coal mining heap in Charleroi (terril l’Epine): a single shrub in 2010 and an additional one in 2011. This species is much more frequent in parts of northwestern France, close to the Belgian frontiers (Verloove 2007). A future naturalization in suitable (thermophilous) habitats in Belgium is not unlikely.
According to Fryer & Hylmö (2009) Cotoneaster lacteus is common in warm temperate zones of both hemispheres. Its ecological preferences in Belgium are still unclear but it seems to be confined to dry and sunny, stony habitats (old walls, coal mining heaps). In Central-Europe (for instance in Germany; see Dickoré & Kasperek 2010) Cotoneaster lacteus is not hardy and unlikely to occur as an escape. In Haute-Savoie (France) it now is the most commonly planted species of Cotoneaster; according to Farille & al. (2010) it is particularly well-adapted to air pollution and disease resistant.
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Literature
Celesti-Grapow L. & al. (2009) Inventory of the non-native flora of Italy. Plant Biosystems 143(2): 386-430.
De Koning J. & van Den Broek (2009) Nederlandse Dendrologie (14th ed.). K.N.N.V.: 547 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].
Farille M.A., Zeller J., Jordan D., Charpin A. & Garraud L. (2010) Cotonéasters échappés de jardins en Haute-Savoie. Monde Pl. 501: 1-5.
Fryer J. & Hylmö B. (2009) Cotoneasters. A comprehensive guide to shrubs for flowers, fruit, and foliage. Timber Press, Portland-London: 344 p.
Klotz G. (1996) Neue oder kritische Cotoneaster Arten: 9. Die weidenblättrigen Felsmispeln (Cotoneaster sect. Densiflos Yü ser. Salicifolii Yü) in der Natur und Kultur. Mitt. Deutsch. Dendrol. Ges. 82: 67-85.
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].
Pyke S. (2008) Contribución al conocimiento de la flora alóctona catalana. Collect. Bot. 27: 95-104 [available online at: http://collectaneabotanica.revistas.csic.es/index.php/collectaneabotanica/issue/view/1].
Roloff A. & Bärtels A. (2006) Flora der Gehölze (2e Auflage). Ulmer, Stuttgart: 844 p.
Stace C. (2010) New Flora of the British Isles, 3th ed.: XXXII + 1232 p. Cambridge University Press.
Verloove F. (2007) La flore urbaine de Dunkerque (Nord): quelques xénophytes remarquables. Monde Pl. 494: 11-14 [available online at: http://alienplantsbelgium.be/sites/alienplantsbelgium.be/files/flore%20urbaine.pdf].