Prunus

The Amur cherry can’t compete with the native bird cherry (Prunus padus) with regard to flowering, but is nevertheless a showy tree due to the bark on branches and trunk. This is a beautiful shiny yellow-coppery colour and exfoliates attractively.

It is a rapid grower, non-suckering and thornless, not particularly tall but with a very broad crown in maturity. Characteristically of many species and cultivars of the Prunus genus, it produces several branches from a single point in the stem, which leads to a tendency to breaking in storms and under heavy snow. On the other hand, even the twisted ruins of an old tree look rather sculptural well beyond the showiness of youth. The autumn leaf colour is a handsome yellow, though the leaves fall early.

In Finland, Amur cherry was long limited to collections until plant production began in the early 1970s. The earliest trees at Mustila were planted around 1910 or soon after, and the largest of these had a trunk 30cms in diameter in 1959. Nowadays there are specimens of several different provenances growing in the Arboretum which differ slightly from each other, for example in the colour of the trunk.

The Russian plantsman Mitšurin crossed the Amur cherry with sour cherry (P.cerasus), producing a tree whose fruit are intermediate in size between those of the parents.

This tree is only known in cultivation. It suckers from its roots, has few or no thorns, and produces edible fruit. Its origins are probably in the area known as the Fertile Crescent, where the diploid Myrobalan or Cherry plum (P. cerasifera) became polyploid. This form was then propagated by grafting starting in the Greco-Roman classical period, at the latest. Cultivation in Finland started over 300 years ago.

The plums are a group of small white-flowering trees which are worth planting even for their flowers alone. The fruit are larger than those of the cherry plum, usually about 4-5 cm wide, and they vary widely in appearance, colour and taste. They are usually divided into three groups, mainly on the basis of their fruit characteristics: the bullace, or damsons (subsp. insititia), mirabelles (subsp. syriaca) and greengages (subsp. italica). Altogether there are about two thousand varieties which are propagated by grafting onto Myrobalan root stock, for example. Traditional old-fashioned red and yellow plum varieties are also propagated using root suckers.

The fruit are used fresh, canned or dried. In the Balkans, for example, dried plums are widely used in producing alcohol (slivovitch). The drying process is on a massive scale, and the varieties used are usually those richest in sugar content.

The brilliantly flowering sour cherry is a small thornless suckering tree whose branches become drooping in maturity. The leaves don’t droop like those of the wild cherry, also called mazzard or gean, (P. avium). The sour cherry blossoms in spring as the leaves break bud, with clusters of 2-5 flowers, and in autumn the fruit ripen to bright, dark or even brownish red. Depending on the flesh of the fruit they are divided into two classes, the clear amarelles and the dark morellos. They can be eaten straight from the tree but their sourness perhaps makes them more suitable for use in preserves.

Though widely cultivated in Eurasia throughout historic times, the sour cherry is nowhere found in the wild. According to the State pomologue Alexandra Smirnoff (1839-1913) the variety ‘Yleinen Ruskeakirsikka’ was in cultivation in south-west Finland in the 1700s. Nowadays dozens of varieties are grown here, one of which is ’Mustilan kirsikka’ or ’Mustilan morelli’, which originated in the orchard of Mustila Manor, next to the Aboretum.

Earlier the sour cherry was grown grafted onto root stock so where old trees have grown there are often thickets or small woods which have developed from suckers when the original tree has died; these can sometimes be found round the ruins of old houses.