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.