Order from Chaos: Linnaeus Disposes

The search for a natural classification system

Efforts to classify plants date back at least to Theophrastus (ca.370–ca.286 B.C.), who described about 480 kinds of plants and grouped them as trees, shrubs, undershrubs and herbs. However, European naturalists in the 16th, 17th and 18th centuries increasingly felt a sense of urgency as they were faced with a bewildering and ever-growing number of previously unencountered plants and animals brought back from European voyages of exploration. Many tried to develop natural classification systems to organize plants and animals according to a "natural order" reflecting their relationships in nature. Such a system would require a complex assessment of numerous essential characteristics of the things being classified. This was extremely difficult, and so some began instead to develop artificial systems that would be easier to apply because they only relied on assessing one or a few characteristics in order to sort and organize living organisms.

In the 16th century, herbalists who tried to describe and partially illustrate all known plants included Otto Brunfels (1464–1534), Leonhard Fuchs (1501–1566), Matthias de L’Obel (1538–1616), John Gerard (1545–1612) and Charles de L’Ecluse (1526–1609). In this same period, Andrea Caesalpino (1519–1603) began to focus on organizing plants by fruits and seeds, including superior and inferior ovaries and the number of locules in an ovary. His work was not well known in his lifetime but was recognized by later botanists like Tournefort, Ray and Linnaeus. Johann Bauhin (1541–1631) treated about 5,000 plants and their synonymies with good diagnoses in his illustrated Historia Plantarum Universalis (Yverdon, 1650–1651). His brother Gaspard (1560–1624) produced a Pinax (Basel, 1623), containing names and synonyms of 6,000 species, and pioneered the use of binomial nomenclature.

In the 17th century, Joseph Pitton de Tournefort (1656–1708) used a form classification that divided plants into groups based on petal characters. His contemporary John Ray (1628–1705) classified some 18,000 species in his Methodus Plantarum (London, 1703), using a system based on form and gross morphology of plant structures.

In the 18th century, Michel Adanson (1727–1806) grouped plants by affinities observed through multiple relationships of characters. His work helped to establish natural classification as a fundamental aim of biology. His contemporary Antoine Laurent de Jussieu (1748–1836) developed a natural classification system, which he paired with Linnaeus’ binomial nomenclature.

At the same time, Linnaeus decided to try an artificial system because he felt there were not enough plants and animals yet known for development of a true natural system. Thus, for botany, he worked out an extremely simple way to classify plants by counting stamens and pistils. The system provided an easy, practical and usable tool for sorting and identifying that even an amateur could use. In its time this and other aspects of his classification system reduced confusion in the study of organisms and facilitated the advancement of botany and zoology by providing a stopgap measure until a natural classification system could be developed.