Medlar trees have been grown in the Oxford Physic Garden since at least 1648; a time when their fruits were much more commonly eaten in England than today. The fruits no doubt contributed to the wide range of produce Jacob Bobart, first Keeper of the Garden, raised and apparently sold in the Oxford market to fund the seventeenth-century Garden.
The medlar is not a native British tree but it has been in cultivation since at least Roman times. At the end of the eighteenth century, the adventurous Oxford professor of botany John Sibthorp thought the tree was native to Germany. In fact, the native distribution of medlar is southwest Asia and southeast Europe. In its native range, it can reach eight metres in height, with fruits about three centimetres in diameter. The most common cultivated types are called Dutch medlars, since they were selected by the Dutch gardeners to have large fruits, at least twice the diameter of the wild plant, and a short stature.
The medlar, the 'dog's bottom', the cul de chien, of orchard trees produces a curious fruit. Technically, it is a pome, a false fruit like the apple, where the true fruit is surrounded by fleshy tissue derived from the receptacle of the mother plant. The medlar is shaped like a flattened sphere, with a large, gapping opening at one end that is surrounded by five, persistent sepals. The ripe fruit is hard and rich in tannins, and only becomes edible once it is bletted, that is softened by frost or storage. During bletting, medlar skins become wrinkled and the flesh goes brown; they appear to be rotting but the flesh becomes aromatic, with a flavour of caramelised apples.
The strange fruit's appearance, and the unusual process needed to make it edible, has given rise to English names, such as openarse, derived from an Old English name, which were used for hundreds of years. Moreover, the medlar has been used in English literature as a symbol of old age, rottenness, decay and even as a reference to whores.
In 1990 a second medlar species, Mespilus canescens, was described. This small tree is endemic to a small region of Arkansas, USA and it very rare. The species' distribution is unexpected, when compared to that of Mespilus germanica. DNA analyses suggest Mespilus canescens is actually a hybrid between introduced Mespilus germanica and a native North American hawthorn (Crataegus).
Baird JR and Thieret JW 1989. The medlar (Mespilus germanica, Rosaceae) from antiquity to obscurity. Economic Botany 43: 328-372.
Lo EYY et al. 2007. Molecular reappraisal of relationships between Crataegus and Mespilus (Rosaceae, Pyreae) - two genera or one? Systematic Botany 32: 596-616.