Prunus


Prunus is a genus of flowering trees and shrubs from the family Rosaceae. The genus includes plums, cherries, peaches, nectarines, apricots and almonds. The genus has a cosmopolitan distribution, being native to the temperate regions of North America, the neotropics of South America, and temperate and tropical regions of Eurasia and Africa, There are about 340 accepted species as of 2024.
Many members of the genus are widely cultivated for their sweet, fleshy fruit and for decorative purposes of their flowers. Prunus fruit are drupes, or stone fruits. The fleshy mesocarp surrounding the endocarp is edible while the endocarp itself forms a hard, inedible shell called the pyrena. This shell encloses the seed, which is edible in some species, but poisonous in many others. Besides being eaten off the hand, most Prunus fruit are also commonly used in processing, such as jam production, canning, drying, and the seeds for roasting.

Description

Members of the genus are either deciduous or evergreen. A few species have spiny stems. The leaves are simple, alternate, usually lanceolate, unlobed, and often with nectaries on the leaf stalk along with stipules. The flowers are usually white to pink, sometimes red, with five petals and five sepals. Numerous stamens are present. Flowers are borne singly, or in umbels of two to six or sometimes more on racemes. The fruit is a fleshy drupe with a single relatively large, hard-coated seed.

Taxonomy

Within the rose family Rosaceae, it was traditionally placed as a subfamily, the Amygdaloideae, but was sometimes placed in its own family, the Prunaceae. More recently, Prunus is thought to have evolved from within a much larger clade now called subfamily Amygdaloideae.

Classification

Evolutionary history

The oldest fossils confirmed to belong to Prunus date to the Eocene, and are found across the Northern Hemisphere. Older potential Late Cretaceous records are unconfirmed.
The earliest known fossil Prunus specimens are wood, drupe, seed, and a leaf from the middle Eocene of the Princeton Chert of British Columbia, Canada. Using the known age as calibration data, a partial phylogeny of some of the Rosaceae from a number of nucleotide sequences was reconstructed. Prunus and its sister clade Maloideae has been suggested to have diverged which is within the Lutetian, or older middle Eocene. Stockey and Wehr report: "The Eocene was a time of rapid evolution and diversification in Angiosperm families such as the Rosaceae...." The oldest fossil species is Prunus cathybrownae from the Klondike Mountain Formation.
The Princeton finds are among a large number of angiosperm fossils from the Okanagan Highlands dating to the late early and middle Eocene. Crataegus is found at three locations: the McAbee Fossil Beds, British Columbia; the Klondike Mountain Formation around Republic, Washington, and the Allenby Formation around Princeton, British Columbia, while Prunus is found at those locations plus the Coldwater Beds of Quilchena, British Columbia and Chu Chua Formation around Chu Chua, British Columbia. A review of research on the Eocene Okanagan Highlands reported that the Rosaceae were more diverse at higher altitudes. The Okanagan highlands formations date to as early as 52 mya, but the 44.3 mya date might still apply. The authors state that "the McAbee flora records a diverse early middle Eocene angiosperm-dominated forest."

Linnean classification

In 1737, Carl Linnaeus used four genera to include the species of modern Prunus—''Amygdalus, Cerasus, Prunus, and Padus—but simplified it to Amygdalus and Prunus'' in 1758. Since then, the various genera of Linnaeus and others have become subgenera and sections, as all the species clearly are more closely related. Liberty Hyde Bailey said: "The numerous forms grade into each other so imperceptibly and inextricably that the genus cannot be readily broken up into species."

Traditional classification

Historical treatments break the genus into several different genera, but this segregation is not currently widely recognised other than at the subgeneric rank. The ITIS recognises just the single genus Prunus, with an open list of species, all of which are given at List of Prunus species.
One treatment of the subgenera derives from the work of Alfred Rehder in 1940. Rehder hypothesized five subgenera: Amygdalus, Prunus, Cerasus, Padus, and Laurocerasus. To them C. Ingram added Lithocerasus. The six subgenera are described as follows:
  • Subgenus Amygdalus, almonds and peaches: axillary buds in threes ; flowers in early spring, sessile or nearly so, not on leafed shoots; fruit with a groove along one side; stone deeply grooved; type species: Prunus amygdalus
  • Subgenus Prunus, plums and apricots: axillary buds solitary; flowers in early spring stalked, not on leafed shoots; fruit with a groove along one side, stone rough; type species: Prunus domestica
  • Subgenus Cerasus, true cherries: axillary buds single; flowers in early spring in corymbs, long-stalked, not on leafed shoots; fruit not grooved, stone smooth; type species: Prunus cerasus
  • Subgenus Lithocerasus, bush cherries: axillary buds in threes; flowers in early spring in corymbs, long-stalked, not on leafed shoots; fruit not grooved, stone smooth; type species: Prunus pumila
  • Subgenus Padus, bird cherries: axillary buds single; flowers in late spring in racemes on leafy shoots, short-stalked; fruit not grooved, stone smooth; type species: Prunus padus, now known to be polyphyletic
  • Subgenus Laurocerasus, cherry laurels: evergreen ; axillary buds single; flowers in early spring in racemes, not on leafed shoots, short-stalked; fruit not grooved, stone smooth; type species: ''Prunus laurocerasus''

    Phylogenetic classification

An extensive phylogenetic study based on different chloroplast and nuclear sequences divides Prunus into three subgenera:
  • Subg. Padus: In addition to species of Padus, this subgenus also includes species of Maddenia, Laurocerasus and Pygeum.
  • Subg. Cerasus: This subgenus includes true cherries such as sweet cherry, sour cherry, mahaleb cherry and Japanese flowering cherry.
  • Subg. Prunus: This subgenus includes the following sections:
  • * Sect. Prunus: Old World plums
  • * Sect. Prunocerasus: New World plums
  • * Sect. Armeniaca: apricots
  • * Sect. Microcerasus: bush cherries
  • * Sect. Amygdalus: almonds
  • * Sect. Persica: peaches
  • * Sect. Emplectocladus: desert almonds

    Species

The lists below are incomplete, but include most more commonly cultivated species.

Afro-Eurasian species

  • P. africana – African cherry
  • P. amygdalus – almond
  • P. apetala – clove cherry
  • P. armeniaca – apricot
  • P. avium – sweet cherry or wild cherry
  • P. brigantina – Briançon apricot
  • P. buergeriana – dog cherry
  • P. campanulata – Taiwan cherry
  • P. canescens – gray-leaf cherry
  • P. cerasifera – cherry plum
  • P. cerasoides – wild Himalayan cherry
  • P. cerasus – sour cherry
  • P. ceylanica – Ceylon cherry
  • P. cocomilia – Italian plum
  • P. cornuta – Himalayan bird cherry
  • P. davidiana – David's peach
  • P. darvasica – Darvaz plum
  • P. domestica – common plum
  • P. fruticosa – European dwarf cherry
  • P. glandulosa – Chinese bush cherry
  • P. grayana – Japanese bird cherry
  • P. incana – willow-leaf cherry
  • P. incisa – Fuji cherry
  • P. jacquemontii – Afghan bush cherry
  • P. japonica – Japanese bush cherry
  • P. laurocerasus – cherry laurel
  • P. lusitanica – Portugal laurel
  • P. maackii – Manchurian cherry
  • P. mahaleb – Mahaleb cherry
  • P. mandshurica – Manchurian apricot
  • P. maximowiczii – Korean cherry
  • P. mume – Chinese plum
  • P. nipponica – Japanese alpine cherry
  • P. padus – bird cherry
  • P. persica – peach
  • P. pseudocerasus – Chinese sour cherry
  • P. prostrata – mountain cherry
  • P. salicina – Japanese plum
  • P. sargentii – north Japanese hill cherry
  • P. scoparia – mountain almond
  • P. serrula – Tibetan cherry
  • P. serrulata – Japanese cherry
  • P. sibirica – Siberian apricot
  • P. simonii – apricot plum
  • P. speciosa – Oshima cherry
  • P. spinosa – blackthorn, sloe
  • P. ssiori – Hokkaido bird cherry
  • P. subhirtella – winter-flowering cherry
  • P. tenella – dwarf Russian almond
  • P. tomentosa – Nanking cherry
  • P. triloba – flowering plum
  • P. turneriana – almondbark
  • P. ursina – Bear's plum
  • P. × yedoensis – Yoshino cherry
  • P. zippeliana – big-leaf cherry

    Species found in the Americas

  • P. alabamensis – Alabama cherry
  • P. alleghaniensis – Allegheny plum
  • P. americana – American plum
  • P. andersonii – desert peach
  • P. angustifolia – Chickasaw plum
  • P. brasiliensis – Brazilian cherry
  • P. buxifolia – chuwacá
  • P. caroliniana – Carolina laurelcherry
  • P. cortapico
  • P. emarginata – bitter cherry
  • P. eremophila – Mojave Desert plum
  • P. fasciculata – wild almond
  • P. fremontii – desert apricot
  • P. geniculata – scrub plum
  • P. gentryi – Gentry cherry
  • P. gracilis – Oklahoma plum
  • P. havardii – Havard's plum
  • P. hortulana – Hortulan plum
  • P. huantensis
  • P. ilicifolia – hollyleaf cherry
  • P. integrifolia
  • P. maritima – beach plum
  • P. mexicana – Mexican plum
  • P. minutiflora – Texas almond
  • P. murrayana – Murray's plum
  • P. myrtifolia – West Indies cherry
  • P. nigra – Canada plum
  • P. occidentalis – western cherry laurel
  • P. pensylvanica – pin cherry
  • P. pleuradenia – Antilles cherry
  • P. pumila – sand cherry
  • P. rigida
  • P. rivularis – creek plum
  • P. serotina – black cherry
  • P. subcordata – Klamath plum
  • P. subcorymbosa
  • P. texana – peachbush
  • P. umbellata – flatwoods plum
  • P. virginiana – chokecherry