However, as cultures merged with each other and plant materials were moved across cultural and geographic lines, it became necessary, for effective cross-cultural communication, to have a universal system of naming plants. This system ensured that corn, even though called maize in another culture, would have a neutral name and mean the same crop to all people.

Some superficial differences automatically place organisms into distinct classes. For example, there are plants and there are animals. In plants, some bear flowers, others do not some have broad leaves, others have narrow leaves; some bear fleshy fruits, others bear grains; and so on. These natural systems of classification are arbitrary and reflect the used human cultures have for plants. Other forms of nomenclature are based on scientific principles that have universal application. This chapter explores the origin and nature of these difference systems for grouping and naming plants.