The term grex (plural greges or grexes; abbreviation gx), derived from the Latin noun , , meaning 'flock', has been expanded in botanical nomenclature to describe hybrids of orchids, based solely on their parentage. 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. Botanical nomenclature of hybrids 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). They can optionally be given Linnean binomials with a multiplication sign "×" before the species epithet for example Crataegus × media. An offspring of a nothospecies, either with a member of the same nothospecies or any of the parental species as the other parent, has the same nothospecific name. The nothospecific binomial is an alias for a list of the ancestral species, whether the ancestry is precisely known or not. For example: a hybrid between Cattleya warscewiczii Rchb.f. 1854 and Cattleya aurea Linden 1883 can be called Cattleya × hardyana Sander 1883 or simply Cattleya hardyana. An offspring of a Cattleya × hardyana pollenized by another Cattleya × hardyana would also be called Cattleya × hardyana. Cattleya × hardyana would also be the name of an offspring of a Cattleya × hardyana pollenized by either a Cattleya warscewiczii or a Cattleya aurea, or an offspring of either a Cattleya warscewiczii or a Cattleya aurea pollenized by a Cattleya × hardyana. × Brassocattleya is a nothogenus including all hybrids between Brassavola and Cattleya. It includes the species Brassocattleya × arauji, also known simply as Brassocattleya arauji, which includes all hybrids between Brassavola tuberculata and Cattleya forbesii. An earlier term was nothomorph for subordinate taxa to nothospecies. Since the 1982 meeting of the International Botanical Congress, such subordinate taxa are considered varieties (nothovars). Horticultural treatment of greges Because many interspecific (and even intergeneric) barriers to hybridization in the Orchidaceae are maintained in nature only by pollinator behavior, it is easy to produce complex interspecific and even intergeneric hybrid orchid seeds: all it takes is a human motivated