The World of Apples

Wild apples

Malus ioensis (Alph.Wood) Britton

Prairie crabapple; Iowa crabapple; Western crabapple

Description

Malus ioensis is a tree, sometimes a shrub, usually 4 to 6 m tall and occasionally 10 m, whose side shoots become spurs or spiny thorns. Its leaves are ovate, usually lobed and toothed, and woolly beneath. The fragrant flowers are 3.5–5 cm across and pink, sometimes fading to white. The fruit is green, sometimes yellow, flattened or round, 2–3 cm across, with a greasy, waxy skin1. Its leaves stay downy beneath and its young shoots are clearly hairy, which distinguishes it from the American and southern crab apples2.

In its native range it flowers in April and May, later than the orchard apple in most regions, and its fruit ripens in September and October1.

Range and habitat

The prairie crab apple grows in the central United States, from South Dakota, Minnesota, Wisconsin and Michigan south to Texas and Louisiana1,3. Its range is centred on the Upper Mississippi valley and extends across the Great Plains2. It grows in woods and thickets, on barrens and hillsides, by streams and lakes, on flood plains and along roadsides, fields and fence lines, from 100 to 300 m1. The IUCN Red List assessed it in 2018 as Least Concern, with a stable population4.

Alphonso Wood named it in 1861, as a variety of the American crab apple, after the state of Iowa2.

Uses

The fruit is extremely sour, but its high pectin content makes a clear yellow jelly1. The Meskwaki made it into jelly and dried it for winter2. Double-flowered forms have been taken into cultivation, among them Bechtel’s crab1, which was planted very widely in North America until the 1970s. The tree reached Kew in 1906; it is susceptible to cedar-apple rust but very resistant to scab2.

Relationship to the cultivated apple

Crosses between the prairie crab apple and the orchard apple have been documented, and their hybrid is named Malus × soulardii1. In a 2017 genome study, M. ioensis was one of a few species with a uniform genetic background, of the kind that has given rise to hybrid species, and the North American species as a group came out closest to the pear6.

Where the sources disagree

  • One species or three. The Flora of North America keeps the prairie crab apple as a species but notes that variation among the eastern North American apples is continuous and that preliminary genetic studies suggest a single species, Malus coronaria5.
  • Ploidy. Polyploid plants have been reported, but it has also been suggested that it is mainly a diploid, sexual species2.

Sources

  1. Malus ioensis, Flora of North America vol. 9, Elizabeth E. Dickson, Flora of North America, eFloras.org. Supports: the description (trees or shrubs (2–)4–6(–10) m, spurs or spiny thorns, leaves tomentose beneath, fragrant flowers 35–50 mm, pink, pome green, sometimes yellow, greasy and waxy, 20–30 mm); flowering April–May and fruiting September–October; habitats and elevation 100–300 m; the states listed; fruit extremely acrid, high in pectin, made into a clear yellow jelly; flowering later than the cultivated apple; artificial hybrids; M. × soulardii as M. ioensis × M. domestica; double-flowered forms, Bechtel's crab and forma fimbriata; the common names.
  2. Malus ioensis, Julian Sutton and Nick Dunn, Trees and Shrubs Online (International Dendrology Society), 2021. Supports: leaves persistently downy beneath and hairy branchlets, distinguishing it from M. coronaria and M. angustifolia; westerly range centred on the Upper Mississippi valley and across the Great Plains; Wood's 1861 epithet for Iowa; suggested to be mainly diploid and sexual, though polyploids reported; jelly and dried fruit of the Meskwaki; introduced to Kew in 1906; Bechtel's crab widely planted in North America until the 1970s; susceptible to rust but very resistant to scab.
  3. Malus ioensis (Alph.Wood) Britton, Plants of the World Online, Royal Botanic Gardens, Kew. Supports: accepted name and authority; native range in the central and east-central United States (the states listed).
  4. Malus ioensis, The IUCN Red List of Threatened Species 2020: e.T64134621A152905585, IUCN SSC Global Tree Specialist Group and Botanic Gardens Conservation International, 2020. Supports: Least Concern, assessed 12 June 2018; population stable.
  5. Malus Mill., Flora of North America vol. 9, Elizabeth E. Dickson, Flora of North America, eFloras.org. Supports: continuous variation in the eastern North American apples; preliminary genetic studies suggesting a single species, M. coronaria.
  6. 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: M. ioensis among the species with a homogeneous genetic background; the North American species closest to pear in the phylogenetic tree.