. Hence, the once widely used term "graft-hybrid" isn't descriptive; it's now frowned upon. Propagation is by cloning only. In practice graft-chimaeras are not noted for their stability and may easily revert back to one of the "parents". Nomenclature Article 21 of the ICNCP stipulates that a graft-chimaera can be indicated either by a formula: the names of both "parents", in alphabetical order, joined by the plus sign "+": » Crataegus + Mespilus a name: if the "parents" belong to different gen… (More on Graft-chimaera)