Cotoneaster ambiguus Rehder & E.H. Wilson, Pl. Wilson. 1: 159, 1912.
Section Acutifolii, series Acutifolii
Origin: China (Sichuan).
Presence in western Europe: Unknown. Not cited by Stace (2010) from Great Britain. Claims from Central-Europe (Dickoré & Kasperek 2010) refer to Cotoneaster villosulus (see below).
Cultivation in Belgium and the Netherlands: Unknown. Keys out to Cotoneaster lucidus Schlechtendal (or, less likely, C. acutifolius Turczaninov) in De Koning & van den Broek (2009) and perhaps cultivated as this in our area. Previous editions of “Nederlandse Dendrologie” (for instance the 4th edition that included several rarely cultivated species; Boom 1959) mentioned a “Cotoneaster ambigua” as a rare ornamental species related to C. lucidus.
Comparative taxonomy: Species accepted by Dickoré & Kasperek (2010) but in a different, much wider sense as to include, among others, Cotoneaster villosulus. Other German authors previously accepted it as a good species (see Klotz 1957; Roloff & Bärtels 2006). The same holds true in the Flora of China (Lingdi & Brach 2003) although these authors also subsume Cotoneaster pseudoambiguus J. Fryer & B. Hylmö under this species.
Illustrations: Roloff & Bärtels (2006).
To our current knowledge Cotoneaster ambiguus is known in Belgium from at least two locations where it is fully naturalized. It was discovered in Antwerpen-Linkeroever in 2010 in spontaneous scrub on sandy rough ground. In 2011 it was also observed on a former demolition site (Groene Vallei) in the city of Gent. In the latter locality it has been confused before with Cotoneaster rehderi, although both species are fairly different. In fact, they only share relatively large, deciduous leaves and lax, more or less many-flowered inflorescences. However, Cotoneaster ambiguus has upper leaf surfaces that are nearly flat (not strongly bullate), inflorescences are only 5-11-flowered (vs. 10-40-flowered) and its berries ultimately turn purplish-black (vs. red). Moreover, at least in Gent where both species grow side by side, their phenology also seems to differ: Cotoneaster ambiguus flowers at least 2 weeks earlier than C. rehderi. Confusion is more likely with the other large-leaved species with purplish-black berries that have been recorded in the wild in Belgium, i.e. Cotoneaster moupinensis and C. villosulus. From the former it is easily distinguished by the number of stones per berry: these are 5 (or 4) in number in Cotoneaster moupinensis and 2 (or 3) in number in C. ambiguus. Moreover, in Cotoneaster moupinensis veins usually are more prominently impressed on the upper leaf surface and inflorescences bear more flowers (see also under that species). Separation from Cotoneaster villosulus is less straightforward (see also under that species). Main distinguishing features are summarized in the table below.
|
C. ambiguus |
C. villosulus |
|
Hypanthium sparsely strigose, glabrescent with age. |
Hypanthium persistently strigose-tomentose. |
|
Inflorescence 5-11-flowered. |
Inflorescence 3-5(-7)-flowered. |
|
Berry 7-9 mm, shiny and sparsely villous. |
Berry 9-11 mm, villous. |
|
Leaves on sterile shoots elliptic to lanceolate, ca. 53-73 x 26-30 mm |
Leaves on sterile shoots elliptic to ovate, ca. 50-65 x 29-36 mm |
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References
Boom B.K. (1959) Nederlandse Dendrologie (4th ed.). Wageningen, Veenman: 480 p.
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].
Klotz G. (1957) Übersicht über die in Kultur befindlichen Cotoneaster-Arten. Wiss. Z. Univ. Halle, Math.-Nat. 6(6): 945-982.
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].
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.