Carolus Linnaeus designed a hierarchical taxonomic system for naming and classifying plants and animals. His system gave each organism a two-term name that was derived from its unique defining characteristics and its position within the hierarchical system. Linnaeus’s classification system brought an intellectual order to biology that persists to this day.
Human dependence on plants and animals has led to classifying living entities into categories as an aid to recognizing useful types. Documents from ancient Egypt, Greece, and Rome contain catalogs of medicinally important plants. The Greek philosopher Aristotle
An 1810 representation of Carolus Linnaeus’s sexual classification system.
During the Renaissance, explorers to distant lands introduced naturalists to a flood of new plants and animals, and this new material provided the impetus for classifying plants and animals according to their relationships to one another rather than their usefulness to humans. Italian physician and botanist Andrea Cesalpino utilized the Aristotelian criteria of essential characteristics (such as reproductive organs) and accidental characteristics (such as taste, smell, and color) to specify features important to plant classification. This approach deeply influenced later naturalists. English Protestant cleric John Ray and French botanist Joseph Pitton de Tournefort helped define the concept of “species” as the most fundamental unit of biological classification, and Tournefort was the first to recognize the “genus” as a basic category of classification, falling between species and families.
However, the discipline of biological classification, otherwise known as taxonomy, suffered from a lack of standardization. The names given to organisms varied from one naturalist to another. To make matters worse, the classification system of Tournefort squeezed the approximately 10,000 known species of plants into 698 genera that botanists had to memorize. Such classification systems were impractical, difficult to use, and detrimental to the effective analysis of the exotic material being supplied by explorers.
Though trained as a physician, Carolus Linnaeus spent the vast majority of his scientific energy on taxonomy. Linnaeus greatly simplified the conventions that governed the naming of plants and animals by using a standardized binomial nomenclature in his seminal work, Systema naturae (1735; A General System of Nature: Through the Three Grand Kingdoms of Animals, Vegetables, and Minerals,
The first half of the binomen consisted of a capitalized genus name, designating a group composed of several species. The second part, a specific epithet, designated the species name. Linnaeus used Latin binomens to replace the long, unwieldy descriptions in Latin used by naturalists at this time. For example, the wild briar rose was known as Rosa sylvestris inordora seu canina (odorless woodland dog rose) or Rosa sylvestris alba cum rubore, folio glabro (pinkish white woodland rose with smooth leaves). Linnaeus simplified these rambling descriptions to Rosa canina. In the tenth edition of A General System of Nature (1758), Linnaeus became the first person to employ binomial nomenclature consistently and without exception to name plants and animals. Because of the simplicity of this naming system, naturalists not only could remember names but also could agree on them.
In A General System of Nature, Linnaeus also described a simple hierarchical system of plant classification anyone could use. He arranged plants into twenty-four “classes” according to the number and relative positions of their male reproductive organs, or stamens. He further divided these classes into sixty-five “orders,” based on the number and position of the female reproductive organs, or pistils. The orders were then divided into genera, or sets of species that shared similar characteristics.
Because of the ease of using Linnaeus’s taxonomic scheme, amateurs, travelers, or gardeners could employ the Linnaean system for themselves and arrive at the same conclusions. Linnaeus also demonstrated the utility of his sexual classification system in a botanical account of his 1732 expedition to Lapland, Flora Lapponica (1737; The Flora of Lapland, 1811), and in his catalog of the plants from the garden of the wealthy amateur horticulturist George Clifford, Hortus Cliffortianus (1738; Clifford’s garden). His later work Species plantarum (1753; Plant Species,
The Linnaean classification system
Linnaeus’s nested hierarchical system received wider use and acceptance than the nonhierarchical schemes proposed by his competitors. For example Georges-Louis Leclerc, comte de Buffon, Linnaeus’s principal competitor, thought that the entire morphology of the organism should be considered when deciding relatedness and not just a few “essential” structures, like the reproductive organs. To encapsulate his approach to classification, Buffon proposed a classification system that joined some organisms by means of physiology, others via anatomy, and still others by means of ecology. Buffon’s system did not endear itself to others because of its almost overwhelming complexity and inability to accommodate new material without substantial changes. By 1799, fifty different classification systems existed, and of these only the taxonomic system created by Linnaeus ultimately survived.
It is difficult to overestimate Carolus Linnaeus’s contribution to biology, since he single-handedly made biological classification a rigorous scientific endeavor. Linnaeus once and for all simplified the naming system and developed a classification scheme that people with a wide range of training could successfully use. His system of taxonomy also easily accommodated the deluge of new biological material from foreign lands, and since its structure did not depend upon the criteria used to distinguish one group from another, the structure of the Linnaean classification system has survived to modern times, even though his sexual classification scheme was abandoned before the end of the eighteenth century.
Linnaeus’s taxonomic scheme, which he viewed as a way of defining the initial species originally placed on Earth by God, ironically paved the way for Charles Darwin’s
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Blair, Charles E. “Latin: A Living Language in the Service of the Study of Life.” Fremontia: A Journal of the California Native Plant Society 31 (2003): 11-17. A brief discussion of the development of plant taxonomy and the role of the Latin language as a standardizing force. -
Blunt, Wilfrid. Linnaeus: The Compleat Naturalist. Princeton, N.J.: Princeton University Press, 2001. A definitive biography on the life and work of Linnaeus by an experienced biographer. -
Fara, Patricia. Sex, Botany, and the Empire: The Story of Carl Linnaeus and Joseph Banks. New York: Columbia University Press, 2003. An idiosyncratic but useful discussion of the work of Linnaeus and its influence on botanist Sir Joseph Banks. -
Farber, Paul Lawrence. Finding Order in Nature: The Naturalist Tradition from Linnaeus to E. O. Wilson. Baltimore: Johns Hopkins University Press, 2000. A lively overview of the history of taxonomy from Linnaeus to modern times. -
Frängsmyr, Tore, ed. Linnaeus: The Man and His Work. Canton, Mass.: Science History, 1994. A collection of essays on Linnaeus’s work and life by Swedish Linnaeus scholars. -
Gould, Stephen J. “Linnaeus’s Luck?” Natural History 109 (2000): 48-76. An examination into why Linnaeus’s classification scheme works so well and why it has accommodated and lent support to Darwin’s theory of evolution. -
Shanahan, Timothy. “Species.” In The Scientific Revolution: An Encyclopedia, edited by Wilbur Applebaum. New York: Garland, 2000. A history of the species concept.
Geoffroy Issues the Table of Reactivities
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First Comprehensive Examination of the Natural World
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Haller Establishes Physiology as a Science
Beginning of Selective Livestock Breeding
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Sir Joseph Banks; Comte de Buffon; Carolus Linnaeus.