Cotoneaster ascendens

Cotoneaster ascendens Flinck & B. Hylmö, Bot. Not. 119: 453, 1966.

Synonyms: C. horizontalis Decaisne var. wilsonii Havemeyer ex E.H. Wilson, C. horizontalis var. ascendens Krüssmann.

Section Adpressi, series Horizontales

Origin: China (Hubei).

Presence in western Europe: Naturalized in Great Britain (Stace 2010). Also known from Scandinavia (Karlsson 2002).

Cultivation in Belgium and the Netherlands: unknown; apparently not separated from Cotoneaster horizontalis by De Koning & van den Broek (2009). Previous editions of the same manual (see for instance Boom 1959) accepted Cotoneaster ascendens as a cultivar of C. horizontalis that is very rarely cultivated.

Comparative taxonomy: Species included in a broadly circumscribed Cotoneaster horizontalis by Dickoré & Kasperek (2010). Other German authors usually accept it as a variety of the latter (see Klotz 1957; Roloff & Bärtels 2006). Although endemic to China not mentioned – not even as a synonym – in the Flora of China (Lingdi & Brach 2003). According to Klotz (1957), this taxon is only known in cultivation.

Illustrations: Hylmö (1993), Grevtsova (1999), Stace (2010).

Cotoneaster ascendens was first recognized in the wild in Belgium in 2010. However, it surely has been widely neglected before as a result of confusion with the related Cotoneaster horizontalis. Up to present it has been reliably recorded from Gent (Verlorenkostbrug, Tolhuisbrug), Menen (on top of old city wall) and Moen (concrete border of canal Kortrijk-Bossuit).

In Belgium, Cotoneaster ascendens always seems to grow on stony substrate (old walls, concrete canal banks), usually in half-shade. In the British Isles, it is confined to open woodland (Stace 2010).

Although not accepted by many recent authors Cotoneaster ascendens is usually readily distinguished from C. horizontalis. It often has a more ascending habit and can grow to 150 (-200) cm tall, its branches have a less distinct herringbone pattern and, above all, it has distinctly larger leaves (14-23 x 8-14 mm) and dark red, larger fruits (7-8 mm across). In Cotoneaster horizontalis, in contrast, leaves are 5-12 x 5-9 mm and fruits orange-red and 5-6 mm across. The main diagnostic features of both species are opposed in the table beneath.

Herbarium specimen 1

Herbarium specimen 2

C. ascendens

C. horizontalis

Leaves 14-23 x 8-14 mm.

Leaves always smaller, 5-12 x 5-9 mm.

Berry dark red at maturity, 7-8 mm across, usually with 2 stones (rarely 3).

Berry orange-red at maturity, 5-6 mm across, usually with 3 stones (rarely 2).

Habit ascending (up to 200 cm tall) with distichous branchlets but without a distinct herringbone pattern.

Habit decumbent to ascending (rarely exceeding 100 cm) with distichous branchlets and a distinct herringbone pattern.


Cotoneaster ascendens, Gent, Verlorenkostbrug, old quay wall of city canal, November 2010, F. Verloove Cotoneaster ascendens, Gent, Verlorenkostbrug, old quay wall of city canal, November 2010, F. Verloove
Cotoneaster ascendens, Gent, Verlorenkostbrug, old quay wall of city canal, November 2010, F. Verloove Cotoneaster ascendens, Gent, Verlorenkostbrug, old quay wall of city canal, November 2010, F. Verloove
Cotoneaster ascendens, Ath, dry, sun-exposed slope (railway siding), July 2011, F. Verloove Cotoneaster ascendens, Ath, dry, sun-exposed slope (railway siding), July 2011, F. Verloove

Literature

Boom B.K. (1959) Nederlandse Dendrologie (4th ed.). Veeman & Zn., Wageningen: 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].

Hylmö B. (1993) Oxbär, Cotoneaster i Sverige. Svensk Bot. Tidskr. 87: 305-330.

Grevtsova A.T. (1999) Atlas Cotoneasters. Cotoneaster (Medic.) Bauhin. Kiev, House Orchard, Truck-Garden: 372 p.

Karlsson T. (2002) Nyheter i den svenska kärlväxtfloran II. Korsblommiga–flockblommiga. Svensk Botanisk Tidskrift 96: 186-206. [available online at: http://sbf.c.se/www/pdf/96(3-4)/Karlsson.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.