Llanelli Naturalists Nwwsletter - Summer 1993 - No 55
George Hutchinson

Some plants grown in gardens have the same name in English and Latin, for example Crocus and Laburnum. Cotoneaster falls into this category. Often known as the ones with red berries in the autumn and liked by birds", they are either deciduous, evergreen or semi-evergreen.

The name is derived from Cotoneum (quince) and the suffix -aster (resembling somewhat) from the similarity of the leaves of some species. Pyracantha with its berries is similar but usually has spiny stems with toothed leaves. The stems of Cotoneaster are not spiny and the leaves are entire.

Most reference works quote about 50 native species worldwide confined to the northern temperate Old World, but this figure is rising as new species are being described and published. The majority of species occur in China, Assam and the Himalayas but there are at least seven in Europe. In fact Wales is about to have its own endemic cotoneaster described - the well known C. integerrimus (Wild Cotoneaster) of the Great Orme, Llandudno is now considered to be different from the continental European population, (the noticeably large leaves of the latter are an obvious character) and has been renamed cambricus (Fryer & Hylmo, 1993).

Horticulturists have been producing new cultivars mostly from the last century onwards as new species were sent back from China and surrounding areas by the great plant-hunters such as Frank Kingdon Ward. New cultivars can occasionally be seen on sale at garden centres and the 1990/91 edition (now superseded) of The Plant Finder lists 91 taxa from British garden centres and nurseries.

The genus contains both very variable, sexual species which hybridise readily ("out-breeders"), much exploited by growers, and less variable, apomictic species ("in-breeders"). Plants found in the wild are mostly bird-sown, often from nearby gardens, but some of the taller cotoneasters found in screen belts around industrial sites have been planted, and are now merging into the natural hedging. The evergreens can become conspicuous in winter. In autumn, red fruit reveal previously unnoticed plants.

Identifying cotoneasters

Taxa range from small ground-cover plants through medium size shrubs to small trees and are often found planted in gardens and parks. The ground cover ones are becoming increasingly popular with local councils for car park surrounds, road schemes, public amenity areas and in raised flower beds to brighten up the modern concrete jungles of town and city centres. Being able to identify these plants gives enjoyment when walking in these areas even though they are all planted. Start in your local park - the author counted 46 plantings of Cotoneaster in Parc Howard, Llanelli on a dark, grey January day.

Having noted the height of the plant one has to check whether it has either open branches, perhaps arching or hanging down, or is a dense impenetrable shrub.

Although flowers are important taxonomically for the classification c41/ Cotoneaster they are present for only a short time each year, mostly in May and June in West Wales, depending on species, so that for most of the year one nas to rely on other characters.

Fruit ripen in late summer and in some species fall early, and in others can linger on until the next season. Again colour is useful, most are red or orange-red when ripe but some can be blackish or pale yellow. Berries can vary from solitary to hanging in small panicles but all these characters are constant for each species.

Leaves on the other hand are continuously present in evergreen plants and over much of the year even in the deciduous species. It is leaves, therefore, which are one of the best characters to study in order to get to grips with Cotoneaster. Features to look for on well-formed leaves are their size and shape, hairiness of the leaf especially on the underside, shininess of the upper surface and whether the main veins are particularly indented into the upper leaf surface.

In fact some cotoneasters can be identified with a high degree of accuracy by examination of only a single leaf.

Identification pitfalls

Once key features are learnt for separating similar species it is important to bear in mind the following pitfalls:

Summer leaves before fruiting are ideal for examining size, hairiness and indentation of venation together. The leaves in spring will be younger and smaller with often more hairs and in autumn leaves may become less hairy. Colour of fruit - wait until fully ripe as initially they are green before turning through orange to red. Some can have blackish berries, and others remain yellow as if immature.

Height - check that the plant is not a young plant which could eventually grow into a tree, or perhaps the plant has been severely pruned.

Species which have been found in natural habitats in Carmarthenshire

Measurements refer to the length of the leaf blade, i.e. excluding the petiole.

C. bullatus (Hollyberry Cotoneaster). A tall open cotoneaster with large broad leaves (3.5 - 7cm) pubescent on lowerside and with upper surface weakly bullate (surface raised into blister-like swellings).

It is an outbreeder and hybridises readily. The key feature is the 4 or often

S nutlets of each fruit; most others have fewer nutlets. C. rehderi is similar (q.v.).

C. frigidus (Tree Cotoneaster). A tall open cotoneaster with large broad leaves (6-13cm) deciduous to semi-evergreen, pubescent on lowerside. Inflorescence usually greater than 20-flowered.

C. hielmgvistii (Hjelmqvist's Cotoneaster). Medium-sized cotoneaster showing a less regular, flat, herring-bone layout to the branches than C. horizontalis and with larger leaves to 1.5(2)cm.

C. horizontalis (Wall Cotoneaster). Small- to medium-sized cotoneaster, depending on habitat, showing a regular, flat herring-bone layout to the branches and with shiny leaves (0.6-1.2cm).

C. integrifolius (Small-leaved Cotoneaster). A dense shrub with tiny obovate (broadest towards apex) leaves (0.4-0.8(1.5)cm), somewhat hairy on the underside. This is the correct name for what was called C.microphyllus. Tire latter name was misapplied for many years and refers to another species not found in the wild in Britain but known from a few botanic gardens. (All labels in garden centres should now read C.integrifolius compare C.consoicuus).

C. rehderi (Bullate Cotoneaster). Similar to C. bullatus but with generally longer leaves (5-12cm) which are strongly bullate, a feature tending to be lost on pressed herbarium specimens, so worth noting in the field. It has recently been confirmed for the County.

C. simonsii (Himalayan Cotoneaster; Khasia Berry). Small- to medium-sized cotoneaster with small rounded leaves (1.5-2.5(3)cm) with pointed apex and slightly pubescent on paler-green underside. This is the commonest cotoneaster found in the wild in Carmarthenshire and was the only one listed by R.F. May (1967). Further research is required to establish whether C. simonsii is the correct name for British material. It recently came to light (Fryer, 1992) that the correct name may be C. khasiensis based on material examined at the Natural History Museum, London, which was originally sent back from the Khasi Hills of Assam by Kingdon Ward and distributed by the New York Botanic Garden (another C. integrifolius/microphyllus problem needing further research). C. sternianus (Stern's Cotoneaster). Of the cotoneasters having a white-hairy underside to the leaf, this is the most commonly planted in parks; similar to C. franchetii with which it has often been confused but with red rather than orange-red fruit when ripe, generally with larger leaves 2.5-5cm compared to 2-3.5cm and leaves coriaceous (leathery)and with veins deeply impressed on upperside, less so in C. franchetii.

Some species found in parks and urban areas but not yet found escaped in the County.

C. conspicuus (Tibetan Cotoneaster). A dense shrub, the tiny elliptical  leaves, much less shiny on the upperside and the somewhat hairy stems distinguishing it from the similar C. integrifolius. It is an outbreeder and can have quite variable sizes to the leaves on the same plant. It has recently been confirmed for Caernarvonshire (vc49) (a first Welsh record).

C. dielsianus    Cotoneaster) White-hairy on the underside of the leaves which are generally smaller than in C. franchetii 1.2-2.5 (3cm) and deciduous. (See also C. sternianus]. Not very commonly planted.

C. franchetii (Franchet's Cotoneaster). One of a group of cotoneasters a dense whitish-hairy underside to the leaves; slightly yellowish-white in this species. Leaves (2-3.5cm) with veins deeply impressed on upperside. Compare C. sternianus and C. dielsianus. The two records of C. franchetii from the county have been shown to be C.sternianus with which it is often confused; there are no other Welsh records.

C. salicifolius (Willow-leaved Cotoneaster). A tall evergreen cotoneaster with several cultivars. The species has long narrow leaves but unlike C. x watereri  the main veins are always noticeably indented below the surface and the leaves are more coriaceous (leathery). It is important to note the height of the plant as the different cultivars range from ground-cover plants to trees. Commonly planted.

C. x suecicus (Swedish Cotoneaster). Cultivar "Skogholm" is one of the commonly planted ground-cover plants in town and city centres and along new roadsides. It has numerous low horizontally arching branches which often reach the ground again; small glabrous leaves and few fruit. Cultivar "Coral Beauty" has similar sized leaves but has some erect branches, often copiously covered in autumn with dense fruit around the branches.

C. x watereri (Waterer's Cotoneaster). A tall semi-evergreen cotoneaster with open branches of which there are a few cultivars. Like C. salicifolius it has long leaves but they are usually slightly broader and the main veins are not deeply impressed on the upperside.

Acknowledgements 

I am grateful to Mrs J. Fryer (a BSBI reference for Cotoneaster) for determining several plants from Carmarthenshire, for supplying instructions for identification, answering queries over several years and giving permission to quote her paper (in press). Also Carmarthenshire recorders, especially R.D.Pryce and I.K.Morgan, for submitted specimens for determination.

References

Fryer, J. (1992). Botanical Society of the British Isles. Cotoneaster Workshop at the Natural History Museum, London.

Fryer, J. & Hylmo, B. The native British Cotoneaster - The Great Orme Berry -renamed Cotoneaster cambricus J. Fryer & B. Hylmo sp.nov. Watsonia (in press).

Lord, A. ed. (1990). The Plant Finder (1990/91 edn). Headmain Ltd. for the Hardy Plant Society, Whitbourne, Worcs.

May, R.F. (1967). A List of the Flowering Plants and Ferns of Carmarthenshire  West Wales Naturalists Trust, Ltd. Haverfordwest.