Malus prunifolia (Willd.) Borkh.

Description

Malus prunifolia is a small tree, 3 to 8 m tall. Its leaves are ovate or elliptic, 5–9 cm long, with finely toothed margins. The flowers are large, 4–5 cm across, white and pink in bud, and open in April and May in China. The fruit is yellow or red and egg-shaped, 2–2.5 cm across, with the sepals still attached, and ripens there in August and September. Plants with 34 and 51 chromosomes have been counted¹.

It is close to the orchard apple, from which it differs in its more sharply toothed leaves, longer flower stalks and fruit crowned by sepals with swollen, fleshy bases². It bears heavy crops, often in alternate years, and is prone to disease³.

Range and habitat

It grows on slopes and plains, from sea level to 1,300 m, in northern and central China, from Liaoning and Inner Mongolia to Qinghai and Guizhou¹. It has been introduced far beyond, to eastern Europe, Central Asia and North America⁵. It reached North America by 1831 and has gone wild in parts of the eastern United States³. The IUCN Red List assessed it in 2014 as Data Deficient⁴.

Uses

In China it is grown for its small, sweet fruit and as a rootstock³, and the Flora of China calls it an excellent stock for grafting apple trees; many varieties have also been bred as fruit trees¹. It is grown worldwide as a rootstock, for its extensive roots, and as a fruit tree and ornamental, and it may be a source of cold tolerance and disease resistance for apple breeders². Russian breeders have used it to improve hardiness to cold, and it was an early parent of ornamental crab apples³.

It was grown in European gardens before it was described, supposedly introduced from Siberia in the 1750s, though it is not known as a wild plant in Russia. Karl Willdenow named it, as a Pyrus, in 1794³.

Relationship to the cultivated apple

A genome study in 2017 found that Malus prunifolia and Malus asiatica are very likely hybrids between the Siberian crab apple and the Asian wild apple from Kazakhstan, and that soft apples of this kind have been grown in China as dessert apples for more than 2,000 years⁶.

Where the sources disagree

• Ancestor or offshoot. A 2015 review lists M. prunifolia, from China, among the likely contributors to the orchard apple⁷; the 2017 genome study treats it instead as a product of the same crossings, a hybrid of the Asian wild apple and the Siberian crab apple⁶.
• Wild or cultivated. Plants of the World Online gives it a native range in northern China⁵, while in Yunnan it is described as semi-cultivated, grown for fruit and as a rootstock³.