The World of Apples

Wild apples

Malus sylvestris (L.) Mill.

European crabapple; Crab apple; Wild crab

Description

Malus sylvestris is a small tree or shrub, usually up to 10 m tall, with branches that are often spiny1. Wild trees live 80 to 100 years and have trunks 23–45 cm across2. The leaves are ovate, elliptic or almost round, 3–11 cm long, hairy on the veins when young and hairless when mature. The flowers are 3–4 cm across, white or pink, and open in late April or May; the fruit is yellow-green, roughly round and 2–3 cm across1, or 1–3 cm in another account3. The flowers are pollinated by insects2.

It is a much less hairy plant than the orchard apple, and its hairless mature leaves help to tell it apart1; the hairiness of the leaf undersides and the width of the fruit are the two main traits used to identify it2.

Range and habitat

The crab apple is native across most of Europe, from Ireland and Portugal to Norway, Finland and European Russia, south to Sicily and the Balkans, and into Türkiye5. It grows from sea level to 1,800 m4.

It is a tree of open places: woodland gaps and edges, farmland hedges and marginal ground, usually as single trees or small groups1,2. It needs a great deal of light and competes poorly, especially with beech, and it favours the wet edge of a forest2. During the last glacial maximum it retreated to refuges in southern Europe, and it recolonised the north when the climate warmed at the start of the Holocene; geneticists recognise three main populations, in western Europe, around the Carpathians and in the Balkans3.

People have gathered its fruit for a very long time. Apple seeds have been found at the Mesolithic site of Staosnaig on Colonsay in Scotland, and tens of thousands at Neolithic villages in central Switzerland6.

The IUCN Red List assessed the crab apple in 2022 as Data Deficient across its global and European range, with its population trend unknown, and lists agriculture, wood plantations and introduced genetic material among its threats4. It is considered endangered in Belgium, the Czech Republic and Germany, and has suffered from the abandonment of coppicing3. The European forest genetic resources programme, EUFORGEN, names its rarity and scattered trees, the grazing of seedlings, hybridisation with orchard apples and the planting of stock of unknown origin as threats, and recommends seed orchards of at least 50 clones for each region2.

Relationship to the cultivated apple

Genetic studies since 2012 show that the European crab apple is the cultivated apple’s major secondary ancestor. Genes have passed in both directions, so that orchard apples are now genetically closer to the crab apple than to their Central Asian progenitor, Malus sieversii7. A genome study in 2017 traced about 21% of the cultivated apple’s genome to M. sylvestris, and found its contribution about 10% higher in fruiting varieties than in rootstocks8. Cider apples, long supposed to descend from crab apples because their small fruit is bitter and astringent, turn out to be no closer to M. sylvestris than dessert apples are3,7.

Genes also flow from orchards into the wild. Wild-growing apples in the Dourdan forest in France and at six sites in the Rhine valley in Germany carry genes of the cultivated apple, and the more they carry, the larger their fruit6. Its genome records a population that has kept on declining9.

Where the sources disagree

  • How much it gave. The EUFORGEN guidelines of 2003 reported German research that found alleles peculiar to the crab apple at high frequencies, and concluded that its genes had rarely, if ever, entered the cultivated apple2. The large studies of 2012 and 2017 found a major contribution7,8.
  • Species or synonym. The Flora of North America lists Malus sylvestris among the synonyms of M. domestica10. Plants of the World Online, the IUCN Red List and the 2022 revision of the genus treat it as a species5,4,12. The name is formally rejected in favour of M. domestica, but remains available when the crab apple is kept as a separate species11.
  • How threatened. The IUCN Red List found too few data to assign a category4; Cornille and colleagues report it endangered in three countries3; and the authors of a 2020 genome study write that it “has been considered as an endangered species in Europe”9.
  • How common. In Britain it has been much over-recorded, because self-sown seedlings of the orchard apple are common and intermediates frequent1.
  • Height. Usually up to 10 m1,2, but trees drawn up in central European forest have exceeded 20 m1.

Sources

  1. Malus sylvestris, Julian Sutton and Nick Dunn, Trees and Shrubs Online (International Dendrology Society), 2021. Supports: the description (small tree or shrub to 10 m, rarely 21 m, branches often spiny, leaves 3–11 cm and glabrous when mature, flowers 3–4 cm in late April or May, fruit yellow-green, 2–3 cm); habitat in woodland gaps and margins; much less hairy than the orchard apple; over-recording in Britain, where wild seedlings of the orchard apple are common and intermediates frequent; tall forest trees over 20 m in central Europe; the common name wild crab.
  2. Technical guidelines for genetic conservation and use: wild apple and pear (Malus sylvestris/Pyrus pyraster), B. Richard Stephan, Iris Wagner and Jochen Kleinschmit, EUFORGEN, International Plant Genetic Resources Institute, 2003. Supports: insect pollinated and quite rare; trees to 10 m with trunks 23–45 cm, living 80–100 years; forest edges, farmland hedges and marginal sites, as single trees or small groups; preference for the wet forest edge; very high light requirement and poor competition, especially with beech; leaf hairiness and fruit width as identifying traits; threats (rarity, grazing of regeneration, hybridisation, seed of unknown origin); seed orchards of at least 50 clones per region; a German study suggesting that M. sylvestris genes had rarely or never entered the cultivated apple.
  3. The domestication and evolutionary ecology of apples, Amandine Cornille and others, Trends in Genetics 30(2): 57–65; Wageningen University repository, 2014. Supports: fruit 1–3 cm; Western and Central European range; retreat to southern glacial refugia and recolonisation of northern Europe in the Holocene; three main populations (western Europe, Carpathians, Balkans); harmed by the abandonment of coppicing; considered endangered in Belgium, the Czech Republic and Germany; cider cultivars not genetically closer to it than dessert cultivars; the name European crabapple.
  4. Malus sylvestris, The IUCN Red List of Threatened Species 2026: e.T172170A213780810, C. Kik, H. Korpelainen, R. Vögel, Å. Asdal, P. Eliáš, D. Draper Munt and J. Magos Brehm, 2026. Supports: Data Deficient, assessed 1 April 2022, global and European scope; population trend unknown; elevation 0–1,800 m; forest, shrubland, grassland and artificial habitats; threats from agriculture, wood plantations and introduced genetic material; the common name crab apple.
  5. Malus sylvestris (L.) Mill., Plants of the World Online, Royal Botanic Gardens, Kew. Supports: accepted species and authority; native range from Europe to Türkiye (the countries listed); introduced in southern Argentina and Queensland; the name marked nom. rej..
  6. Origins of the Apple: The Role of Megafaunal Mutualism in the Domestication of Malus and Rosaceous Trees, Robert N. Spengler, Frontiers in Plant Science 10: 617, 2019. Supports: Mesolithic apple seeds at Staosnaig on Colonsay, Scotland; tens of thousands of apple seeds at Neolithic villages in central Switzerland; crop-to-wild gene flow in the Dourdan forest (France) and at six Rhine valley sites (Germany), with larger fruit where introgression is greater.
  7. New Insight into the History of Domesticated Apple: Secondary Contribution of the European Wild Apple to the Genome of Cultivated Varieties, Amandine Cornille and others, PLoS Genetics 8(5): e1002703, 2012. Supports: M. sylvestris a major secondary contributor; bidirectional gene flow making the cultivated apple genetically closer to it than to M. sieversii; cider cultivars no closer to it than dessert cultivars.
  8. Genome re-sequencing reveals the history of apple and supports a two-stage model for fruit enlargement, Naibin Duan and others, Nature Communications 8: 249, 2017. Supports: about 21% of the cultivated apple's genome from M. sylvestris; introgression about 10% higher in scion cultivars than in rootstocks.
  9. Phased diploid genome assemblies and pan-genomes provide insights into the genetic history of apple domestication, Xuepeng Sun and others, Nature Genetics 52: 1423–1432, 2020. Supports: M. sylvestris one of the two major progenitors; its populations continued to decline, which the authors relate to its being "considered as an endangered species in Europe".
  10. Malus domestica, Flora of North America vol. 9, Elizabeth E. Dickson, Flora of North America, eFloras.org. Supports: Malus sylvestris (Linnaeus) Miller listed among the synonyms of M. domestica.
  11. Madrid Code Appendices I–VII: Appendix IV (Malus domestica), John H. Wiersema, Department of Botany, National Museum of Natural History, Smithsonian Institution. Supports: Malus sylvestris (L.) Mill. (1768) listed among the names rejected in favour of the conserved M. domestica; a rejected heterotypic synonym restored when treated as a distinct species.
  12. A revision of the genus Malus Mill. (Rosaceae), Jing-chao Li, Jian-quan Liu and Xin-fen Gao, European Journal of Taxonomy 853: 1–127, 2022. Supports: M. sylvestris accepted as one of 26 wild species.