Cotoneaster Explained

Cotoneaster [1] is a genus of flowering plants in the rose family, Rosaceae, native to the Palaearctic region (temperate Asia, Europe, north Africa), with a strong concentration of diversity in the genus in the mountains of southwestern China and the Himalayas.[2] They are related to hawthorns (Crataegus), firethorns (Pyracantha), photinias (Photinia), and rowans (Sorbus).

Depending on the species definition used, between 70 and 300 different species of Cotoneaster are described, with many apomictic microspecies treated as species by some authors, but only as varieties by others.[2] [3]

The majority of species are shrubs from 0.5- tall, varying from ground-hugging prostrate plants to erect shrubs; a few, notably C. frigidus, are small trees up to 15m (49feet) tall and 75cm (30inches) trunk diameter. The prostrate species are mostly alpine plants growing at high altitudes (e.g. C. integrifolius, which grows at 3000- in the Himalayas), while the larger species occur in scrub and woodland gaps at lower altitudes.

Description

The shoots are dimorphic, with long shoots (10- long) producing structural branch growth, and short shoots (0.5- long) bearing the flowers; this pattern often developing a 'herringbone' form of branching. The leaves are arranged alternately, 0.5- long, ovate to lanceolate in shape, entire; both evergreen and deciduous species occur.

The flowers are produced in late spring through early summer, solitary or in corymbs of up to 100 together. The flower is either fully open or has its five petals half open 5- diameter. They may be any shade from white through creamy white to light pink to dark pink to almost red, 10–20 stamens and up to five styles. The fruit is a small pome 5- diameter, pink or bright red, orange or even maroon or black when mature, containing one to three (rarely up to five) seeds.[3] [4] Fruit on some species stays on until the following year.

Wildlife value

Cotoneaster species are used as larval food plants by some Lepidoptera species including grey dagger, mottled umber, short-cloaked moth, winter moth, and hawthorn moth. The flowers attract bees and butterflies and the fruits are eaten by birds.

Although only a single species is native there, in the UK and Ireland, Cotoneaster species are, along with the related genus Pyracantha, a source of nectar. The red berries are also highly attractive to blackbirds and other thrushes.

Cultivation and uses

Cotoneasters are very popular garden shrubs, grown for their attractive habit and decorative fruit. Some cultivars are of known parentage, such as the very popular Cotoneaster × watereri Exell (Waterer's cotoneaster; C. frigidus × C. salicifolius), while others are of mixed or unknown heritage.[4]

The following species and cultivars have gained the Royal Horticultural Society's Award of Garden Merit:-

Invasiveness

Many species have escaped from cultivation and become invasive weeds where climatic conditions are suitable for them, such as the many Chinese species naturalised in northwestern Europe. C. glaucophyllus has become an invasive weed in Australia[16] and California.[17] C. simonsii is listed on the New Zealand National Pest Plant Accord preventing its sale and distribution because of its invasiveness. On Portland, Dorset, UK, it has become invasive and is regularly culled to prevent damage to the Jurassic Coast.

Nomenclature and classification

The genus name Cotoneaster derives from cotoneum, a Latin name for the quince, and the suffix -aster, 'resembling'. The name is correctly masculine, though in some older works it was wrongly treated as feminine, resulting in different name endings for many of the species (e.g.Cotoneaster integerrima instead of Cotoneaster integerrimus).[3]

The genus is often divided into two or more sections, though the situation is complicated by hybridisation:[3]

Edibility

All Cotoneaster berries are eaten by many birds. Like most other small, red berries, they are evolved to have birds spread the seeds widely and are not good for humans to eat. The Children's Hospital of Philadelphia lists Cotoneaster berries as poisonous[18]

Selected species

Sources:[2] [20] [21] [22] [23]

External links

Notes and References

  1. Sunset Western Garden Book, 1995:606–607
  2. Flora of China: Cotoneaster (includes most of the world's Cotoneaster species) www.efloras.org
  3. Bean, W. J. (1976). Trees and Shrubs Hardy in the British Isles 8th edition. John Murray .
  4. Huxley, A., ed. (1992). New RHS Dictionary of Gardening. Macmillan .
  5. Web site: Cotoneaster atropurpureus 'Variegatus' . RHS . 5 May 2020.
  6. Web site: Cotoneaster conspicuus 'Decorus' . RHS . 5 May 2020.
  7. Web site: Cotoneaster 'Cornubia' . RHS . 5 May 2020.
  8. Web site: Cotoneaster lacteus . RHS . 5 May 2020.
  9. Web site: Cotoneaster procumbens 'Queen of Carpets' . RHS . 5 May 2020.
  10. Web site: Cotoneaster 'Rothschildianus' . RHS . 5 May 2020.
  11. Web site: Cotoneaster salicifolius 'Gnom' . RHS . 5 May 2020.
  12. Web site: Cotoneaster salicifolius 'Pink Champagne' . RHS . 5 May 2020.
  13. Web site: Cotoneaster sternianus . RHS . 5 May 2020.
  14. Web site: Cotoneaster × suecicus 'Coral Beauty' . RHS . 5 May 2020.
  15. Web site: Cotoneaster × suecicus 'Juliette' . RHS . 5 May 2020.
  16. http://www.weeds.org.au/cgi-bin/weedident.cgi?tpl=plant.tpl&state=&ibra=all&card=S01 Weeds Australia – Weed Identification – Cotoneaster
  17. http://www.cal-ipc.org/ip/management/ipcw/pages/detailreport.cfm@usernumber=36&surveynumber=182.php Cal-IPC: Invasive Plants of California's Wildlands.
  18. Web site: Poisonous Berries . 5 May 2014 .
  19. Applequist, W.L.. 2012. Report of the Nomenclature Committee for Vascular Plants: 64. Taxon. 61. 5. 1108–1117. 10.1002/tax.615019. free.
  20. Flora of NW Europe: Cotoneaster species list
  21. Flora of Nepal: Cotoneaster www.efloras.org
  22. Flora Europaea: Cotoneaster rbg-web2.rbge.org.uk
  23. Den virtuella floran: Cotoneaster linnaeus.nrm.se(in Swedish)

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