M. domestica is the correct name for the orchard apples in general, and for escapes and naturalised trees deriving from them. Superficially, they are remarkably uniform in their essential botanical characters but there is no doubt that they are of hybrid origin. They have in common the following characters: young stems covered with woolly down. Leaves dull green, elliptic-ovate, usually rounded at the base, densely woolly beneath, margins irregularly saw-toothed. Flower-stalks, calyx-tube, and outside of calyx woolly. Fruits indented at the base and usually so at the apex; calyx persistent in fruit.
The domestic apple has evolved, under human influence, from various species found wild in Europe and Asia – all of them belonging to the series Pumilae. Those to which it shows the greatest resemblance are M. dasyphylla Borkh. of the Danube basin and N. Balkans; M. praecox (Pallas) Borkh. of European Russia; and M. sieversii (Ledeb.) Roem. of Russian Central Asia (the resemblance to this last is said to be very close). Other species that have made their contribution are M. sylvestris and M. prunifolia.
The orchard apples do not, of course, come within the scope of this work, but some with flowers of a deeper pink than ordinary have been recommended for garden planting. Such, for example, are the cooker ‘Arthur Turner’ and the dual-purpose ‘Upton Pyne’.
Crab apples. – The word ‘crab’ was originally used for the native species (M. sylvestris) and for sour-fruited seedlings of the orchard varieties, but was extended later to the various exotic species of Malus and today has become in effect the vernacular word for Malus, with the exclusion only of the orchard apples. But there is a group of garden varieties for which the term ‘crab apple’ rather than ‘crab’ (in the modern sense) could be used. These derive from the orchard apples, many of them (especially the American and Canadian varieties) by deliberate crossing with various “Siberian” crabs, which were probably M. × robusta and not the true Siberian crab (M. baccata). The Astrakhan apples and M. prunifolia were also used, the object of North American breeders being to produce apples hardy enough to withstand the harsh winters of the prairie states. A few of these are cultivated as ornamentals for their decorative fruits, notably ‘Dartmouth’ and ‘Hyslop’, described in the section on hybrids. In the same section see also ‘John Downie’, ‘Fairy’, and ‘Veitch’s Scarlet’, all raised in Britain. Some hybrids, known collectively as the Quarrenden hybrids, were raised in the last century by Philip Fry of Maidstone, Kent, by crossing the dessert apple ‘Devonshire Quarrenden’ with a “Siberian” crab.
M. × adstringens Zab. ex Rehd. – This name is really of no service in horticultural nomenclature but appears in several manuals and must be mentioned. The parentage was originally given by Zabel as M. dasyphylla × M. baccata, without description. Rehder gave the first parent as M. pumila (under which he included the orchard apples) and referred to this group various hybrid crabs raised in the USA from the crossing of orchard apples with “Siberian” crab. See further above.
M. × astracanica Dum.-Cours. Astrakhan Apple. – The astrakhan apples appear to be primitive forms of garden apple showing what is probably the influence of M. prunifolia in their more deeply toothed leaves, and their longer-stalked and often bloomy fruits. Miller knew the White Astrakhan or Transparent apple, introduced from Russia about the middle of the 18th century. In this the fruits are translucent yellow with a red tinge on one side. In the Red Astrakhan, which is, or was until recently, still cultivated as an orchard variety in the USA, the fruits are a bright red, covered with plum-like bloom, long-stalked. In both the fruits are conical.