The World of Apples

Wild apples

Malus × floribunda Siebold ex Van Houtte

Japanese flowering crab

Description

Malus × floribunda is a small tree or shrub up to 10 m tall with wide-spreading branches. Its leaves are ovate, 4–8 cm long and sharply toothed, sometimes three- or five-lobed on long shoots. The flowers come in clusters of four to seven on hairy purple stalks; they are 2.5–3 cm across, deep carmine in bud, opening pale pink and fading to white, in April and May in Britain. The calyx falls before the fruit ripens; the fruit is round, yellowish to red and only 6–9 mm across1. It has yellow anthers and sharply toothed leaves, which distinguish it from Malus halliana2.

It flowers abundantly, but it is somewhat susceptible to powdery mildew and fire blight and is increasingly disfigured by scab in summer1.

Origin

It is unknown as a wild plant, and its seedlings are very variable; most botanists now regard it as a hybrid, probably between Malus toringo and Malus baccata1. Philipp von Siebold introduced it to Europe from Japanese gardens in the 19th century, though the date is not known1, and it was published in 18653. When Makino described Malus spontanea in 1914, he suggested that it might have had a part in the origin of this crab4.

Relationship to the cultivated apple

Early in the 20th century C. S. Crandall made many crosses between crab apples and large-fruited apples at the University of Illinois6, one of them between a tree catalogued as Malus floribunda 821 and the variety Rome Beauty5. In 1943 a graduate student, L. Fredric Hough, noticed that resistance to apple scab was segregating among Crandall’s seedlings, and from 1945 he worked with J. Ralph Shay of Purdue University6. In that year breeders at Illinois and Purdue began a disease-resistance programme with two scab-resistant seedlings of the 821 cross; Rutgers University later joined it, until 1987, and the first variety, Prima, was released in 19705. The resistance came into the cultivated apple after four or more generations of crossing back to orchard varieties7. By 2000 the programme had released 18 scab-resistant varieties carrying the Vf gene from M. floribunda 821, and breeders around the world had released about 50 varieties from its material6.

Where the sources disagree

  • Where it comes from. Plants of the World Online gives Korea as its native range3; Trees and Shrubs Online and the Flora of North America say that wild populations are unknown and that it is probably a cultivated selection1,2.
  • Its parents. The usual view is that it is a hybrid, probably of Malus toringo and Malus baccata1; Makino suggested a part for Malus spontanea4. Some horticultural writers have treated it as a species1.

Sources

  1. Malus × floribunda, Julian Sutton and Nick Dunn, Trees and Shrubs Online (International Dendrology Society), 2021. Supports: the description (small tree or shrub to 10 m with wide-spreading branches, leaves 4–8 cm, sharply toothed, sometimes 3- or 5-lobed on long shoots, 4–7 flowers on hairy purple pedicels 2.5–4 cm, flowers 2.5–3 cm, deep carmine buds opening pale pink and ageing to white in April–May in the UK, calyx falling, fruit globose, 6–9 mm, yellowish to red); some susceptibility to powdery mildew and fire blight, and increasingly to scab; unknown as a wild plant, with very variable seedlings; a hybrid by modern consensus, probably M. toringo × M. baccata; introduced to Europe from Japanese cultivation by Siebold in the 19th century, the date unknown; treated as a species by some horticultural writers; the common name Japanese Flowering Crab.
  2. Malus halliana, Flora of North America vol. 9, Elizabeth E. Dickson, Flora of North America, eFloras.org. Supports: M. floribunda distinguished from M. halliana by yellow anthers, sharply serrulate leaves folded in bud and fruit impressed at both ends; its geographic origin unknown, with no documented wild populations; possibly of hybrid origin and probably a cultivated selection rather than a natural species.
  3. Malus × floribunda Siebold ex Van Houtte, Plants of the World Online, Royal Botanic Gardens, Kew. Supports: accepted as a hybrid, published 1865 in the Journal Général d'Horticulture; native range given as Korea; introduced in Great Britain, New York and Vermont.
  4. Malus spontanea, Julian Sutton and Nick Dunn, Trees and Shrubs Online (International Dendrology Society), 2021. Supports: Makino's suggestion, in describing M. spontanea in 1914, that it might have played a part in the origin of M. × floribunda.
  5. Disease-Resistant Apple Cultivars Developed from the Apple Breeding Program at the University of Illinois, S. S. Korban and P. A. O'Connor, University of Illinois Agricultural Experiment Station Bulletin 790; IDEALS, 1990. Supports: crosses between crabapples and large-fruited apples early in the 20th century at Illinois, including M. floribunda 821 × Rome Beauty; in 1945 breeders at Illinois and Purdue began the disease-resistance programme with two scab-resistant seedlings from that cross; Rutgers in the programme until 1987; Prima, the first cultivar, released in 1970.
  6. History of the PRI apple breeding program, J. Janick, Acta Horticulturae 595 (abstract), International Society for Horticultural Science, 2002. Supports: the programme traced to C. S. Crandall's crosses at the University of Illinois early in the 20th century; segregation for scab resistance noticed by L. Fredric Hough in 1943 and published in 1944; collaboration with J. Ralph Shay at Purdue from 1945; by 2000, 18 scab-resistant cultivars carrying the Vf gene from M. floribunda 821 released by the programme, and about 50 cultivars from its germplasm released worldwide.
  7. The vulnerability of US apple (Malus) genetic resources, Gayle M. Volk and others, Genetic Resources and Crop Evolution 62: 765–794; USDA GRIN, 2015. Supports: the PRI programme's scab-resistant cultivars carrying a resistance allele from M. floribunda after four or more generations of introgression.