Sorbus pseudomeinichii Sorbus pseudomeinichii Sorbus pseudomeinichii, known as false rowan and Catacol whitebeam, is a rare tree endemic to the Isle of Arran in south west Scotland. It is believed to have arisen as a hybrid of the native rowan ("Sorbus aucuparia") and the cut-leaved whitebeam ("Sorbus pseudofennica") which is in turn a rowan/Arran whitebeam ("Sorbus arranensis") hybrid. Only two specimens of the Catacol whitebeam are known, making it the rarest tree in Scotland and also the United Kingdom. A third was recorded as a sapling but is believed to have been destroyed by deer. A seedling has also been grown in
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