Prunus spinosa the British Army, blackthorn sticks are carried by commissioned officers of the Royal Irish Regiment; this is a tradition also in Irish regiments in some Commonwealth countries. The leaves resemble tea leaves, and were used as an adulterant of tea. Shlomo Yitzhaki, a Talmudist and Tanakh commentator of the High Middle Ages, writes that the sap (or gum) of "P. spinosa" (which he refers to as the ) was used as an ingredient in the making of some inks used for manuscripts. The fruit stones have been found in Swiss lake dwellings. Evidence of the early use of sloes by
Prunus avium parent species of "Prunus cerasus" (sour cherry), by way of ancient crosses between it and "Prunus fruticosa" (dwarf cherry) in the areas where the two species overlap. All three species can breed with one another. "Prunus cerasus" is now a species in its own right, having developed beyond a hybrid and stabilised. Pliny distinguishes between "Prunus", the plum fruit, and "Cerasus", the cherry fruit. Already in Pliny quite a number of cultivars are cited, some possibly species or varieties, Aproniana, Lutatia, Caeciliana, and so on. Pliny grades them by flavour, including dulcis ("sweet") and acer ("sharp"). and goes so far