Photinia

Photinias typically grow from 4–15 m tall, with a usually irregular crown of angular branches; the branches are often (not always) thorny. The leaves are alternate, entire or finely toothed, varying between species from 3–15 cm in length and 1.5–5 cm wide; the majority of species are evergreen but several are deciduous. The flowers are produced in early summer in dense terminal corymbs; each flower is 5–10 mm diameter, with five rounded white petals; they have a mild, hawthorn-like scent. The fruit is a small pome, 4–12 mm across, bright red and berry-like, produced large quantities, maturing in the fall and often persisting well into the winter. The fruit are consumed by birds, including thrushes, waxwings and starlings; the seeds are dispersed in their droppings. Photinia species are sometimes used as food plants by the larvae of some Lepidoptera species including common emerald, feathered thorn and setaceous Hebrew character. Photinias are subject to leaf blight. https://homeguides.sfgate.com/photinia-blight-43033.html. ==Taxonomy==

Some botanists also include the closely related North American species Heteromeles arbutifolia in Photinia — as Photinia arbutifolia. The genus Stranvaesia is so similar in morphology to Photinia that its species have sometimes been included within it, but recent molecular data indicate that the two genera are not closely related. The genus Aronia has been included in Photinia in some classifications, but recent molecular data confirm that these genera are not closely related. Other close relatives include the firethorns (Pyracantha), cotoneasters (Cotoneaster) and hawthorns (Crataegus). A number of species have been moved to the separate genus Stranvaesia including P. amphidoxa, P. davidiana, P. nussia, and P. tomentosa. ==Uses==

Photinias are very popular ornamental shrubs, grown for their fruit and foliage. Numerous hybrids and cultivars are available; several of the cultivars are selected for their strikingly bright red young leaves in spring and summer. The most widely planted are: • Photinia × fraseri (P. glabra × P. serratifolia) - red tip photinia, Christmas berry :*Photinia × fraseri 'Little Red Robin', a plant similar to 'Red Robin', but dwarf in stature with an ultimate height/spread of around 2–3 ft :*Photinia × fraseri 'Camilvy' :*Photinia × fraseri 'Curly Fantasy' :*Photinia × fraseri 'Super Hedger' - a newer hybrid with strong upright growth :*Photinia × fraseri 'Pink Marble' also known as 'Cassini', a new cultivar with rose-pink tinted new growth and a creamy-white variegated margin on the leaves :*Photinia × fraseri 'Robusta' • Photinia 'Redstart' (P. davidiana × P. × fraseri) • Photinia 'Palette' (parentage unknown) • Photinia davidiana 'Fructu Luteo' (fruit yellow) • Photinia davidiana 'Prostrata' (a low-growing form) ==Toxicity==

Some varieties of Photinia are toxic due to the presence of cyanogenic glycosides in the vacuoles of foliage and fruit cells. When the leaves are chewed these compounds are released and are rapidly converted to hydrogen cyanide (HCN) which blocks cellular respiration. The amount of HCN produced varies considerably between taxa, and is in general greatest in young leaves. Ruminants are particularly affected by cyanogenic glycosides because the first stage of their digestive system (the rumen) provides better conditions for liberating HCN than the stomachs of monogastric vertebrates. ==Species list==

27 species are accepted by Plants of the World Online . • Photinia anlungensis • Photinia arbutifolia • Photinia berberidifolia • Photinia chihsiniana • Photinia chingiana • Photinia chingshuiensis • Photinia chiuana • Photinia crassifolia • Photinia cucphuongensis • Photinia davidiana • Photinia fokienensis • Photinia × fraseri • Photinia glabra • Photinia griffithii • Photinia hirsuta • Photinia impressivena • Photinia integrifolia • Photinia lanuginosa • Photinia lindleyana • Photinia lochengensis • Photinia loriformis • Photinia megaphylla • Photinia microphylla • Photinia prionophylla • Photinia prunifolia • Photinia serratifolia • Photinia stenophylla • Photinia taishunensis • Photinia tushanensis • Photinia wrightiana Extinct species A small group of extinct species have been described from the Asian, European, and North American fossil records. • †Photinia eratonis Langhian, Styria, Austria • †Photinia kodorica Pliocene, Kodor river, Abkhazia/Georgia • †Photinia pageae Ypresian, Eocene Okanogan Highlands, Western North America • †Photinia sarmatiaca (replacement name for Photinia acuminata ) Serravallian, Rostov region, Russian Federation • †Photinia szaferi Tortonian, Mirotstowice Dolne, Lower Silesia, Poland Formerly placed here • Pourthiaea arguta (as Photinia arguta ) • Pourthiaea beauverdiana (as Photinia beauverdiana ) • Pourthiaea pustulata (as Photinia pustulata ) • Pourthiaea sorbifolia (as Photinia sorbifolia ) • Pourthiaea zhejiangensis (as Photinia zhejiangensis ) • Stranvaesia lasiogyna (as Photinia lasiogyna ) • Weniomeles atropurpurea (as Photinia atropurpurea ) • Weniomeles bodinieri (as Photinia bodinieri ) ==References==