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Chapter 5: Fruit trees and nuts

Definite evidence for their cultivation [the apple, pear, plum, and cherry]
only appears in the 1st millennium bc and their extensive incorporation into
horticulture seems to have taken place only in Greek and Roman times....A
plausible explanation for the late appearance of these 'second wave' fruit
domesticates is that they do not lend themselves to simple vegetative
propagation [unlike the olive, grape vine, fig, date palm, and pomegranate,
which can be propagated through cuttings]. Their culture is based almost
entirely on grafting....The adoption of clonal cultivation means that most
fruit trees, in the 5 or 6 millennia since their introduction into
cultivation, have undergone very few sexual cycles. In other words,
selection could only have operated during a limited number of generations,
and we have to expect that the cultivars have not diverged considerably from
their progenitors' gene-pools.

Cherries: Prunus avium and P. cerasus

The sweet cherry, P. avium [cherries liked by birds!] is a rather tall
tree...with sweet, round, red-black berries....The cultivated clones of the
sweet cherry [P. avium] are closely related to a group of wild and feral
forms which are widely distributed over temperate Europe....The sour cherry,
P. cerasus, is a smaller tree...with bright red berries and a characteristic
acid taste....The earliest report of cherry cultivation appears in classical
times. Pliny tells that Lucullus, in the first century BC, introduced to
Rome a superior cherry variety which he obtained in the Pontus
region...Large quantities of cherry stones were found in both Roman and
Medieval contexts in Germany as well as other central European countries.