 Grex names are one of the three categories of plant names governed by the International Code of Nomenclature for Cultivated Plants; within a grex the "cultivar group" category can be used to refer to plants by their shared characteristics (rather than by their parentage), and individual orchid plants can be selected (and propagated) and named as cultivars.The horticultural nomenclature of grexes exists within the framework of the botanical nomenclature of hybrid plants.Interspecific hybrids occur in nature, and are treated under the International Code of Nomenclature for algae, fungi, and plants as nothospecies, ('notho' indicating hybrid).