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 ursina It is usually present in too small a quantity to do any harm but any very bitter seed or fruit should not be eaten. Consumption of small quantities of hydrogen cyanide stimulates respiration and improves digestion. Excessive consumption of the toxin can cause respiratory failure and death. "Prunus ursina" fuits better in full sun but is still successful in partial shade. The tree will form suckers if its shallow roots are damaged. Among the pests that affect the "prunus" genus is honey fungus. the seed requires 2–3 months cold stratification in order to germinate. Prunus ursina Prunus ursina (bear's plum,