Cotoneaster (Cotoneaster) is a genus of woody 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. They are related to the hawthorns (Crataegus), firethorns (Pyracantha), photinias (Photinia) and rowans (Sorbus).
Depending on the species definition used, there are between 70-300 species of cotoneaster, with many apomictic microspecies treated as species by some authors, but only as varieties by others.
The majority of species are shrubs from 0.5–5 m tall, varying from ground-hugging prostrate plants to erect shrubs; a few, notably C. frigidus, are small trees up to 15 m tall and 75 cm trunk diameter. The prostrate species are mostly alpine plants growing at high altitude (e.g. C. integrifolius, which grows at 3000–4000 m in the Himalaya), while the larger species occur in scrub and woodland gaps at lower altitudes.
The shoots are dimorphic, with long shoots (10–40 cm long) producing structural branch growth, and short shoots (0.5–5 cm long) bearing the flowers; this pattern often developing a 'herringbone' form of branching. The leaves are arranged alternately, 0.5–15 cm long, ovate to lanceolate, entire; both evergreen and deciduous species occur. The flowers are produced in late spring, solitary or in corymbs of up to 100 together; they are 5–10 mm diameter, and have five petals, creamy white to light pink, 10-20 stamens and up to five styles. The fruit is a small pome 5–12 mm diameter, bright red when mature, containing one to three (rarely up to five) seeds.
The species are divided into two or more sections:
- Cotoneaster sect. Cotoneaster. Flowers solitary or up to 5 together; petals forward-pointing, often tinged pink. Mostly smaller shrubs.
- C. horizontalis
- C. integrifolius (syn. C. microphyllus var. thymifolius)
- C. intergerrimus
- C. microphyllus
- Flowers 5-15 together in corymbs. Mostly larger shrubs.
- C. bullatus
- Cotoneaster sect. Chaenopetalum. Flowers more than 20 together in corymbs; petals opening flat, creamy white. Mostly larger shrubs.
- C. affinis
- C. coriaceus
- C. frigidus - Himalayan Tree Cotoneaster
- C. glabratus
- C. glaucophyllus
- C. harrovianus
- C. rhytidophyllus
- C. salicifolius
- C. turbinatus
Cotoneasters are very popular garden shrubs, grown for their attractive habit and decorative fruit. Many of the garden shrubs are cultivars, some of hybrid origin; some of known parentage, others not.
Pests and diseases
- Entomosporium maculatum
- Phyllosticta cotoneastri
- Woolly Apple Aphid: Eriosoma lanigerum
- Hawthorn Lacebug: Corythuca cydoniae
- Apple Maggot: Rhagoletis pomonella
- Sinuate Peartree Borer: Agrilus sinuatus (Europe, Eastern North America)
- Roundheaded Appletree Borer: Saperda candida
- Black Vine Weevil: Otiorhynchus sulcatus
- Leaf Crumpler: Acrobasis indigenella
- Cotoneaster Webworm: Arthrips rancidella (Europe, Western North America)
- w:Grey Dagger
- w:Mottled Umber
- w:Short-cloaked Moth
- w:Winter Moth.
- Pearslug: Caliroa cerasi
Cotoneaster integrifolius detail.jpg
Cotoneaster integrifolius leaf and fruit (8 mm diameter) detail