Malus sieversii (Ledeb.) M. Roem.

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Credits

Julian Sutton (species), Nick Dunn (cultivars)

Recommended citation
Sutton, J. & Dunn, N., 'Malus sieversii' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/malus/malus-sieversii/). Accessed 2021-05-11.

Genus

Synonyms

  • Pyrus sieversii Ledeb.

Glossary

germplasm
Seed.
IUCN
World Conservation Union (formerly the International Union for the Conservation of Nature).
USDA
United States Department of Agriculture.
Extinct
IUCN Red List conservation category: ‘there is no reasonable doubt that the last individual [of taxon] has died’.

Credits

Julian Sutton (species), Nick Dunn (cultivars)

Recommended citation
Sutton, J. & Dunn, N., 'Malus sieversii' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/malus/malus-sieversii/). Accessed 2021-05-11.

Small tree to 10(–14) m, branches sometimes spiny. Bark grey. Young branchlets often red-tinted, more or less hairy; buds dark red, ovoid. Leaf blades ovate, elliptic or oblong, 6–11 × 3–5.5 cm, densely hairy below at first, becoming less so, sparsely hairy only on the veins above; base cuneate to rounded; apex acute; margin bluntly toothed, sometimes entire at base; petiole 1.2–3.5 cm, somewhat hairy. Inflorescence a 3–6-flowered corymb, 4–6 cm across; pedicels ~1.5 cm, white-tomentose. Flowers 3–4 cm diameter, April-May; sepals ~6 mm, lanceolate, acuminate, densely tomentose on both surfaces, reflexed, persistent; petals white or pink, obovate, 1.5–2 cm; stamens 20, unequal, about half as long as petals; styles hairy up to the middle, as long as or slightly longer than the stamens. Fruit yellow-green, 3–8 cm in diameter, variably tinged red, globose but sometimes flattened, elongated, angled or ribbed, August-October. (Gu et al. 2003Yuzepchuk 1971).

Distribution  China W Xinjiang Iran possibly KazakhstanKyrgyzstanTajikistanUzbekistan

Habitat Mountain forests and slopes, sometimes the dominant tree; 1100–2400 m asl.

USDA Hardiness Zone 4-8

RHS Hardiness Rating H6

Conservation status Vulnerable (VU)

Malus sieversii is the most celebrated wild apple of Central Asia, forming a major part of the fruit forests in the Tian Shan, as well as occurring in other forest types. It is threatened by habitat loss and degradation; fruit forest now exists only as remnants (IUCN 2020; Juniper & Mabberley 2019). It is the primary progenitor of the cultivated apple, M. domestica, and apparently also of M. asiatica.

M. sieversii was first described by Carl Ledebour (as a Pyrus) in 1830, from specimens collected in Khazakstan during 1793 by the short-lived Johann Sievers, a participant in an early Russian expedition to the mountains of Central Asia. Altogether a hairier plant than the European M. sylvestris, it forms part of a taxonomically difficult and incompletely understood complex. In particular, M. kirghisorum and M. turkmenorum (q.v.) are sometimes separated as distinct species; the extent of the geographical range of M. sieversii rather depends on the status of these forms. The line between wild and domesticated apples in Central Asia is not always clear cut.

Wild M. sieversii is remarkably diverse in horticulturally significant ways (Juniper & Mabberley 2019). Trees may be very spiny, or not at all. The flowers may be white, pink or rarely almost red (f. niedzwetzkiana, below). Fruits vary widely in size, colour, texture, flavour (including sweetness, bitterness, sourness but also more subtle elements – Baraniuk 2016), and in whether or not they are held on the tree into the winter. The apples are much harvested, very selectively, by local people. Aside from humans, bears and horses seem to be the main seed dispersers (Juniper & Mabberley 2019) although it seems possible that the evolution of large fruit was driven by megafauna which became extinct during the Pleistocene (Spengler 2019).

Wild M. sieversii populations probably contain genetic diversity which would be valuable in apple breeding, perhaps for disease resistance or tolerance of extreme environments. Many wild collections have been made for research and breeding purposes, initially mainly into Russian cultivation, more recently by Americans too (Forsline et al. 2003). When these collections leak out into wider cultivation, mainly in arboreta and botanic gardens, they tend to be labelled M. sieversii. Without knowing their provenance it would be impossible to say that they were not seedling M. domestica, some of which may anyway be essentially unhybridized, very lightly selected M. sieversii. Conversely, those who prefer to lump these wild apples into a broadly drawn M. domestica would so label them; the most detailed examination of records would be needed to discover which might be wild M. sieversii.

The UK and Irish champion (7 m × 103 cm, 2018) is one of a group of three planted in 1992 at the Yorkshire Arboretum, from a seed collection made in Uzbekistan (The Tree Register 2020; J. Grimshaw pers. comm. 2020). Another of similar age at Jodrell Bank, Cheshire was measured at 4 m × 38 cm in 2015 (The Tree Register 2020). Several specimens (Kazakhstan and Tajikistan provenance) are grown in behind-the-scenes areas at RBG Edinburgh (Royal Botanic Garden Edinburgh 2020).

In continental Europe, specimens are recorded at Gothenburg Botanic Garden, Sweden and Ghent University Botanical Garden, Belgium, from Kyrgistan and Kazakhstan respectively (Gothenburg Botanical Garden 2020; Plantcol 2020). In North America around 500 accessions of M. sieversii (taken here to include M. kirghisorum and M. turkmenorum) are grown at the US National Clonal Germplasm Repository, Geneva, NY (USDA/ARS, National Genetic Resources Program 2020). Relatively young, grafted specimens of some of these can be seen at the Arnold Arboretum, MA (Arnold Arboretum 2020).


f. niedzwetzkyana (Dieck) Langenf.

Synonyms
Malus niedzwetzkyana Dieck
Malus sieversii 'Niedzwetzkyana'
Malus pumila 'Niedzwetzkyana'
Malus 'Almata'

Flowers purple-red; young leaves and branchlets purple; fruit purple with a purple bloom and red flesh. (Yuzepchuk 1971Juniper & Mabberley 2019).

Highly pigmented trees otherwise resembling M. sieversii are found occasionally in wild populations, especially in Kazakhstan; they are highly prized and tend to be lifted and sold locally as ornamentals while still young (Juniper & Mabberley 2019, Wilson et al. 2019).

The taxonomic status of this tree is controversial. It was initially described as a species by Georg Dieck in 1891, who had received it in Germany from the Russian lawyer and naturalist Vladislav Niedzwiecki, exiled to Kazakhstan. Since then horticulturalists (Jacobson 1996) and botanists (Yuzepchuk 1971) have cast strong doubt on its validity as a species. At one extreme, Juniper & Mabberley (2019) suggest that because multiple genes probably influence the location and intensity of anthocyanin pigmentation in the species, f. niedzwetzkyana may simply be the result of a particular set of alleles coming together by chance in seedlings. If this is the case, harvesting of these individuals might not be such a threat to its long term existence as is sometimes supposed. On the other hand, it is occasionally still treated as a full – and endangered – species. Wilson et al. (2019) do just this, assessing its undoubted rarity with conservation in mind.

There seem to have been two linked introductions to cultivation. The material sent to Dieck apparently established the plant in Europe (Bean 1981), but Niels Hansen of the State Agricultural Experiment Station, Brookings, SD also received it from Niedzwiecki in 1897 while prospecting in Central Asia for plants suitable for the northern Great Plains (Fiala 1994). Hansen’s introduction has been the more important in subsequent breeding. It is not clear how uniform are wild trees given this name, and the two introductions, both from Niedzwiecki, are probably closely related. In addition to the above description, in cultivated trees the red pigmentation extends into the wood, the mature leaf has a green blade with red midrib and petiole, and the fruit is 5–6 cm in diameter (Bean 1981, Fiala 1994). Hansen (fide Fiala 1994) described it as a ‘good juicy, subacid, eating apple’ while Bean (1981) disparages its ‘rather turnip-like consistency’. Very significantly, it is highly susceptible to scab, as are many but not all crabs bred from it (Fiala 1994).

This tree has been most important in the breeding of crabs with intensely coloured flowers and/or pigmented leaves. Such hybrids, especially those involving M. baccata, are often referred to as rosyblooms. Hansen’s own ‘Hopa’ (see Cultivars G-I) and several selected by Isabella Preston in Ottawa were early examples (Fiala 1994). Separately, M. × purpurea is a cultivated hybrid between M. sieversii f. niedzwetzkyana and M. × atrosanguinea.

Not often seen in Europe, The Tree Register (2020) records a specimen of 8 m × 64 cm (2019) at Thenford House, Brackley, Northamptonshire, and it is occasionally offered by nurseries. Once widely planted in North America, it has now been dropped by the nursery trade (Jacobson 1996) in favour of more disease-resistant hybrids. Older trees can still be seen; the Arnold Arboretum has a pair of grafted specimens dating from 1953, one 55 cm basal diameter in 2015 (Arnold Arboretum 2020).