The World of Apples

Wild apples

Malus coronaria (L.) Mill.

American crabapple; Sweet crabapple; Fragrant crabapple; Garland tree

Description

Malus coronaria is a small tree or shrub, 2.5 to 7.5 m tall and sometimes 10 m, whose side shoots become short spurs or spiny thorns. Its leaves are ovate, triangular or lanceolate and very variable: some are lobed, others not, with toothed margins. The flowers, 2.5–4 cm across, are pink, sometimes fading to white, with pink, salmon or purple anthers. The fruit is a flattened green or yellow-green globe 1.5–3 cm across, occasionally 5.5 cm, with many stone cells around the core. Plants with 34, 51 and 68 chromosomes in their body cells have been counted1.

In its native range it flowers in May, sometimes from April or into June, and the fruit ripens in September and October1. The flowers are fragrant, and late enough in some places to open in early June3.

Range and habitat

The American crab apple grows in Ontario and in the eastern United States, west to Wisconsin and Kansas and south to Georgia, Alabama and Louisiana1,4; it is absent from Florida and New England3. It grows in open woods, at forest edges, in thickets, along stream banks, in fields, fence rows and roadsides, from 50 to 1,000 m1. The IUCN Red List assessed it in 2018 as Least Concern, with a stable population5.

Uses

Linnaeus described it in 1753 as Pyrus coronaria, making it the first North American apple to be named scientifically, and Miller moved it to his genus Malus in 1768. Indigenous peoples used it for food and medicine; the Iroquois dried the fruit for winter. Settlers in Ontario probably used its hard wood for the gear teeth of grist mills, and for tool handles. It reached England in 1724 and was grown in Pennsylvania by about 1750. In gardens it is grown for its scented flowers, but it is very susceptible to cedar-apple rust3. Double-flowered forms have been found in the wild and taken into cultivation1.

Relationship to the cultivated apple

The eastern North American apples form a section of their own, Chloromeles, set apart by features of the flower and fruit2. Where M. coronaria meets the orchard apple, a hybrid called Malus × platycarpa may arise3. From 1987 the United States’ national apple collection began gathering the four wild North American species6.

Where the sources disagree

  • How many species. The Flora of North America keeps three eastern species, M. coronaria, M. angustifolia and M. ioensis, as morphological extremes, but notes that preliminary genetic studies suggest one species, M. coronaria2. Early in the 20th century Rehder named several more species from variations in leaf shape, among them M. lancifolia, M. glabrata and M. glaucescens; they are now treated as synonyms1.
  • Hybrid or synonym. The Flora of North America lists M. platycarpa, named for large-fruited plants with slightly lobed leaves, as a synonym of M. coronaria1; Trees and Shrubs Online treats Malus × platycarpa as a hybrid with the orchard apple, while noting that its hybrid status is not universally accepted3.
  • Ploidy. The Flora of North America records 34, 51 and 68 chromosomes1; Trees and Shrubs Online describes it as primarily tetraploid3.

Sources

  1. Malus coronaria, Flora of North America vol. 9, Elizabeth E. Dickson, Flora of North America, eFloras.org. Supports: the description (trees or shrubs 2.5–7.5(–10) m, spurs or spiny thorns, variable leaves, flowers 25–40 mm, pink, anthers pink to purple, pome green or yellow-green, 15–30(–55) mm, 2n = 34, 51, 68); flowering (April–)May(–June) and fruiting September–October; habitats and elevation 50–1,000 m; Ontario and the states listed; Rehder's segregate species (M. lancifolia, M. glabrata, M. glaucescens, M. platycarpa) now treated as synonyms; double-flowered wild forms; the common names.
  2. Malus Mill., Flora of North America vol. 9, Elizabeth E. Dickson, Flora of North America, eFloras.org. Supports: sect. Chloromeles defined by unique floral and fruit traits; continuous variation blurring species boundaries; preliminary genetic studies suggesting a single species, M. coronaria; polyploidy and apomixis; three morphological extremes kept as species.
  3. Malus coronaria, Julian Sutton and Nick Dunn, Trees and Shrubs Online (International Dendrology Society), 2021. Supports: fragrant flowers in May or early June; first North American apple described scientifically, by Linnaeus in 1753 as Pyrus coronaria, moved to Malus by Miller in 1768; used as food and medicine by indigenous peoples, the Iroquois drying the fruit for winter; wood presumably used for gear teeth in early Ontario grist mills, and for tool handles; primarily tetraploid, with diploid and triploid individuals reported; brought to England in 1724 and grown in Pennsylvania by about 1750; core range in the Great Lakes area; susceptibility to cedar-apple rust; the hybrid M. × platycarpa, whose status is not universally accepted; absent from Florida and New England.
  4. Malus coronaria (L.) Mill., Plants of the World Online, Royal Botanic Gardens, Kew. Supports: accepted name and authority; native range "SE. Canada to NC. & E. U.S.A."; introduced in Minnesota.
  5. Malus coronaria, The IUCN Red List of Threatened Species 2020: e.T64134541A152907593, IUCN SSC Global Tree Specialist Group and Botanic Gardens Conservation International, 2020. Supports: Least Concern, assessed 12 June 2018; population stable.
  6. 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: collecting of four North American wild Malus species from 1987 for the US national collection; the need to assess how well the three species of central and eastern North America are represented.