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 lusitanica and Oregon as invasive. It is thought to have spread from cultivated areas into natural areas by birds who consume and defecate the fruits away from the source plant. It has gained the Royal Horticultural Society's Award of Garden Merit. The leaves of "Prunus lusitanica" contain cyanide and will release this into the environment if burnt or if crushed. The fruit is somewhat edible if fully ripe, but if it is bitter, it is toxic and should not be eaten. Prunus lusitanica Prunus lusitanica, the Portugal laurel, is a species of the genus "Prunus", related to the cherry. It is