Rowan is attested from the 1520s in the sense "fruit of the service tree", adopted via French "sorbe" from Latin "sorbum" "service-berry". "Sorbus domestica" is also known as "whitty pear", the adjective whitty meaning "pinnate". The name "mountain-ash" for "Sorbus domestica" is due to a superficial similarity of the rowan leaves to those of the ash, not to be confused in "Fraxinus ornus", a true ash that is also known as "mountain ash". "Sorbus torminalis" is also known as "chequer tree"; its fruits, formerly used to flavour beer, are called "chequers", perhaps from the spotted pattern of the fruit. The name
Sorbus torminalis the bark on old trees. The species has sometimes been placed in its own genus, "Torminalis". Recent molecular phylogenetics confirms an earlier taxonomic opinion that the genus "Sorbus" as defined in the broad sense is not monophyletic, but the simple-leafed species traditionally included in "Sorbus" are a monophyletic group; this species would be included in a clade called "Aria" (genus "Aria" or "Sorbus" subgenus "Aria") as the species "Aria torminalis" Beck. It is a sexually reproducing diploid species that forms diploid and polyploid hybrids with members of subgenus "Aria" (whitebeams). A number of often very localised stable apomictic polyploid species