It was not until Roman times that cultigens would be given the names needed to distinguish one from another. Botanical historian Morton notes that Theophrastus refers to wheat varieties (Historia Plantarum VIII, 1, 2-7) and Roman agricultural writer Columella (4- c. 70 CE) mentions selections of carrots (De Re Rustica ix,4,6).
Botanical historian William Stearn attributes the first named cultigens to the Roman statesman Cato the Elder (234–149 BCE) who, writing in his De Agri Cultura in about 160 BCE, named 120 different kinds of what we would now call cultivars (cultivated varieties) of figs, grapes, apples and olives.
In the modern era Linnaeus, while working on his theory of plant classification and nomenclature, was constantly frustrated by the different colours and forms of garden cultigens so beloved by the gardening community. He disparagingly called these people ‘anthophiles’ (flower lovers): ‘ .. botany has been overborne by the system of varieties for long enough … few, if any, agree as to what constitutes a species, or what a variety; … I wish the system of varieties were entirely excluded from Botany and turned over entirely to the Anthophiles, since it causes nothing but ambiguities, errors, dead weight and vanity …’ (Linnaeus 1737) adding much later ‘… no botanist in his senses will enlist in their camp’ (Linnaeus 1751, aphorism 310, transl. Stafleu 1971). For Linnaeus cultigens were not a part of God’s natural order. ‘All the species recognized by Botanists came forth from the Almighty Creator’s hand, and the number now and always will be exactly the same, while every day new and different florist’s species arise from the true species recognized by botanists, and when they have arisen they eventually revert to their original forms.’ (Linnaeus 1751, aphorism 310, transl. Stafleu 1971).
Following the initial systematization of plant nomenclature by Linnaeus, further order was put into the developing chaos of plant names when the Lois de la Nomenclature Botanique (Laws of Botanical Nomenclature) were established at an International Botanical Congress convened in Paris in 1867. This system of nomenclatural rules has been regularly updated and is now known as the International Code of Nomenclature for algae, fungi, and plants (ICN), the current title coined at a Botanical Congress in Melbourne in 2011.
Although the difficulties with cultigens noted by the acerbic Linnaeus persisted, it would take until 1953, a date we can assign to the beginning of cultivated plant taxonomy, before his wish for a separate code would be granted with the publication of the first, Wageningen, International Code of Nomenclature for Cultivated Plants (ICNCP), abbreviated to Cultivated Plant Code. This was followed by seven subsequent editions – in 1958 (Utrecht), 1961 (update of 1958), 1969 (Edinburgh), 1980 (Seattle), 1995 (Edinburgh), 2004 (Toronto), and the latest in 2009 (Wageningen).
Cultigens are defined in the Cultivated Plant Code as plants ‘… whose origin or selection is primarily due to the intentional actions of mankind’ and they use of the special classification categories cultivar, Group and grex, which are names similar to ranking names like family, genus, and species in the ICNCP. The ICNCP names, sometimes called variety names, like Apple ‘Jonathan’ or Malus ‘Jonathan’, are in non-Latin form which helps the gardeners, nurserymen, farmers, foresters who use them. Wild plant taxonomy and cultigen taxonomy are both about the science of plant names but the former is plant-centred and the latter is human-centred, recalling the theme of studying plants either for their own sake or for their utility, as pure and applied science.
In general cultigen names are distinguished by having cultigen epithets – names, often in English, that supplement the usual Latin names and are presented within quotation marks. For example the cultivars Rosa ‘Peace’, Camellia x williamsii ‘Anticipation’ (which are cultigens) can be distinguished from the non-manipulated plants Cornus capitata, Quercus robur, Cedrus deodara, and Eucalyptus crenulata, the latter three species found both in the wild and in cultivation.