The history of plant systematics—the

biological classification In biology, taxonomy () is the scientific study of naming, defining ( circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxa (singular: taxon), and these groups are give ...

plant Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they are predominantly Photosynthesis, photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with c ...

s—stretches from the work of ancient Greek to modern

evolutionary biologists Evolutionary biology is the subfield of biology that studies the evolutionary processes such as natural selection, common descent, and speciation that produced the diversity of life on Earth. In the 1930s, the discipline of evolutionary bi ...

. As a field of science, plant systematics came into being only slowly, early plant lore usually being treated as part of the study of medicine. Later, classification and description was driven by

natural history Natural history is a domain of inquiry involving organisms, including animals, fungi, and plants, in their natural environment, leaning more towards observational than experimental methods of study. A person who studies natural history is cal ...

and

natural theology Natural theology is a type of theology that seeks to provide arguments for theological topics, such as the existence of a deity, based on human reason. It is distinguished from revealed theology, which is based on supernatural sources such as ...

. Until the advent of the theory of evolution, nearly all classification was based on the

scala naturae The great chain of being is a hierarchical structure of all matter and life, thought by medieval Christianity to have been decreed by God. The chain begins with God and descends through angels, humans, animals and plants to minerals. The great ...

. The professionalization of botany in the 18th and 19th century marked a shift toward more holistic classification methods, eventually based on evolutionary relationships.

Antiquity

The peripatetic philosopher

Theophrastus Theophrastus (; ; c. 371 – c. 287 BC) was an ancient Greek Philosophy, philosopher and Natural history, naturalist. A native of Eresos in Lesbos, he was Aristotle's close colleague and successor as head of the Lyceum (classical), Lyceum, the ...

(372–287 BC), as a student of

Aristotle Aristotle (; 384–322 BC) was an Ancient Greek philosophy, Ancient Greek philosopher and polymath. His writings cover a broad range of subjects spanning the natural sciences, philosophy, linguistics, economics, politics, psychology, a ...

Ancient Greece Ancient Greece () was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity (), that comprised a loose collection of culturally and linguistically r ...

, wrote '' Historia Plantarum'', the earliest surviving treatise on plants, where he listed the names of over 500 plant species.''Concise Encyclopedia Of Science And Technology'', McGraw-Hill He did not articulate a formal classification scheme, but relied on the common groupings of

folk taxonomy A folk taxonomy is a vernacular name, naming system, as distinct from Taxonomy (general), scientific taxonomy. Folk biological classification is the way people traditionally describe and organize the world around them, typically making generous us ...

combined with growth form: tree shrub; undershrub; or herb. The ''

De Materia Medica (Latin name for the Greek work , , both meaning "On Medical Material") is a pharmacopoeia of medicinal plants and the medicines that can be obtained from them. The five-volume work was written between 50 and 70 CE by Pedanius Dioscorides, ...

'' of

Dioscorides Pedanius Dioscorides (, ; 40–90 AD), "the father of pharmacognosy", was a Greek physician, pharmacologist, botanist, and author of (in the original , , both meaning "On Materia medica, Medical Material") , a 5-volume Greek encyclopedic phar ...

was an important early compendium of plant descriptions (over five hundred), classifying plants chiefly by their medicinal effects.

Medieval

The

Byzantine The Byzantine Empire, also known as the Eastern Roman Empire, was the continuation of the Roman Empire centred on Constantinople during late antiquity and the Middle Ages. Having survived the events that caused the fall of the Western Roman E ...

emperor

Constantine VII Constantine VII Porphyrogenitus (; 17 May 905 – 9 November 959) was the fourth Byzantine emperor of the Macedonian dynasty, reigning from 6 June 913 to 9 November 959. He was the son of Emperor Leo VI and his fourth wife, Zoe Karbonopsina, an ...

sent a copy of

' pharmacopeia to the

Umayyad The Umayyad Caliphate or Umayyad Empire (, ; ) was the second caliphate established after the death of the Islamic prophet Muhammad and was ruled by the Umayyad dynasty. Uthman ibn Affan, the third of the Rashidun caliphs, was also a membe ...

Caliph Abd al-Rahman III who ruled Córdoba in the 9th century, and also sent a monk named Nicolas to translate the book into Arabic. It was in use from its publication in the 1st century until the 16th century, making it one of the major

herbal A herbal is a book containing the names and descriptions of plants, usually with information on their medicinal, Herbal tonic, tonic, culinary, toxic, hallucinatory, aromatic, or Magic (paranormal), magical powers, and the legends associated wi ...

s throughout the Middle Ages. The

taxonomy image:Hierarchical clustering diagram.png, 280px, Generalized scheme of taxonomy Taxonomy is a practice and science concerned with classification or categorization. Typically, there are two parts to it: the development of an underlying scheme o ...

criteria of medieval texts is different from what is used today. Plants with similar external appearance were usually grouped under the same species name, though in modern taxonomy they are considered different.Middle East Garden Traditions: Unity and Diversity: Questions, Methods and Resources in a Multicultural Perspective Volume 31
/ref> Abū l-Khayr's botanical work''Umdat al-tabib fi ma'rifat al-n abat (Medical support for the knowledge of plants by all experts)'' is the most complete Andalusi botanical text known to modern scholars. It is noted for its detailed descriptions of

plant morphology Phytomorphology is the study of the physical form and external structure of plants.Raven, P. H., R. F. Evert, & S. E. Eichhorn. ''Biology of Plants'', 7th ed., page 9. (New York: W. H. Freeman, 2005). . This is usually considered distinct from pl ...

and

phenology Phenology is the study of periodic events in biological life cycles and how these are influenced by seasonal and interannual variations in climate, as well as habitat factors (such as elevation). Examples include the date of emergence of leav ...

Early modern period

In the 16th century, works by Otto Brunfels,

Hieronymus Bock Hieronymus Bock ( Latinised Hieronymus Tragus; c. 1498 – 21 February 1554) was a German botanist, physician, and Lutheran minister who began the transition from medieval botany to the modern scientific worldview by arranging plants by their re ...

, and

Leonhart Fuchs Leonhart Fuchs (; 17 January 1501 – 10 May 1566), sometimes spelled Leonhard Fuchs and cited in Latin as ''Leonhartus Fuchsius'', was a German physician and botanist. His chief notability is as the author of a large book about plants and thei ...

helped to revive interest in natural history based on first-hand observation; Bock in particular included environmental and life cycle information in his descriptions. With the influx of exotic species in the

Age of Exploration The Age of Discovery (), also known as the Age of Exploration, was part of the early modern period and overlapped with the Age of Sail. It was a period from approximately the 15th to the 17th century, during which Seamanship, seafarers fro ...

, the number of known species expanded rapidly, but most authors were far more interested in the medicinal properties of individual plants than an overarching classification system. Later influential Renaissance books include those of Caspar Bauhin and

Andrea Cesalpino Andrea Cesalpino ( Latinized as Andreas Cæsalpinus) (1524/1525 – 23 February 1603) was a Florentine physician, philosopher and botanist. In his works he classified plants according to their fruits and seeds, rather than alphabetically or ...

. Bauhin described over 6000 plants, which he arranged into 12 books and 72 sections based on a wide range of common characteristics. Cesalpino based his system on the structure of the organs of fructification, using the Aristotelian technique of logical division. In the late 17th century, the most influential classification schemes were those of English botanist and natural theologian

John Ray John Ray Fellow of the Royal Society, FRS (November 29, 1627 – January 17, 1705) was a Christian England, English Natural history, naturalist widely regarded as one of the earliest of the English parson-naturalists. Until 1670, he wrote his ...

and French botanist

Joseph Pitton de Tournefort Joseph Pitton de Tournefort (5 June 165628 December 1708) was a French botanist, notable as the first to make a clear definition of the concept of genus for plants. Botanist Charles Plumier was his pupil and accompanied him on his voyages. Li ...

. Ray, who listed over 18,000 plant species in his works, is credited with establishing the

monocot Monocotyledons (), commonly referred to as monocots, (Lilianae ''sensu'' Chase & Reveal) are flowering plants whose seeds contain only one Embryo#Plant embryos, embryonic leaf, or cotyledon. A monocot taxon has been in use for several decades, but ...

dicot The dicotyledons, also known as dicots (or, more rarely, dicotyls), are one of the two groups into which all the flowering plants (angiosperms) were formerly divided. The name refers to one of the typical characteristics of the group: namely, ...

division and some of his groups— mustards,

mints A mint or breath mint is a food item often consumed as an after-meal refreshment or before business and social engagements to improve breath odor. Mints are commonly believed to soothe the stomach, given their association with natural byproducts ...

legumes Legumes are plants in the pea family Fabaceae (or Leguminosae), or the fruit or seeds of such plants. When used as a dry grain for human consumption, the seeds are also called pulses. Legumes are grown agriculturally, primarily for human consu ...

and

grasses Poaceae ( ), also called Gramineae ( ), is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos, the grasses of natural grassland and species cultivated in ...

—stand today (though under modern family names). Tournefort used an artificial system based on logical division which was widely adopted in France and elsewhere in Europe up until Linnaeus. The book that had an enormous accelerating effect on the science of plant systematics was ''

Species Plantarum ' (Latin for "The Species of Plants") is a book by Carl Linnaeus, originally published in 1753, which lists every species of plant known at the time, classified into genus, genera. It is the first work to consistently apply binomial nomenclature ...

'' (1753) by

Linnaeus Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...

. It presented a complete list of the plant species then known to Europe, ordered for the purpose of easy identification using the number and arrangement of the male and female sexual organs of the plants. Of the groups in this book, the highest rank that continues to be used today is the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

. The consistent use of

binomial nomenclature In taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, altho ...

along with a complete listing of all plants provided a huge stimulus for the field. Although meticulous, the classification of Linnaeus served merely as an identification manual; it was based on

phenetics In biology, phenetics (; ), also known as taximetrics, is an attempt to classify organisms based on overall similarity, usually with respect to morphology or other observable traits, regardless of their phylogeny or evolutionary relation. It is ...

and did not regard evolutionary relationships among species. It assumed that plant species were given by God and that what remained for humans was to recognise them and use them (a Christian reformulation of the ''scala naturae'' or ''Great Chain of Being''). Linnaeus was quite aware that the arrangement of species in the ''Species Plantarum'' was not a natural system, i.e. did not express relationships. However he did present some ideas of plant relationships elsewhere.

Modern and contemporary periods

Significant contributions to plant classification came from de Jussieu (inspired by the work of

Michel Adanson Michel Adanson (7 April 17273 August 1806) was an 18th-century French botanist and naturalist who traveled to Senegal to study flora and fauna. He proposed a "natural system" of taxonomy distinct from the binomial system forwarded by Linnaeus. ...

) in 1789 and the early nineteenth century saw the start of work by de Candolle, culminating in the ''Prodromus''. A major influence on plant systematics was the theory of

evolution Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, re ...

(

Charles Darwin Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English Natural history#Before 1900, naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all speci ...

published ''

Origin of Species ''On the Origin of Species'' (or, more completely, ''On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life'')The book's full original title was ''On the Origin of Species by M ...

'' in 1859), resulting in the aim to group plants by their

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

relationships. To this was added the interest in

plant anatomy Plant anatomy or phytotomy is the general term for the study of the internal Anatomy, structure of plants. Originally, it included plant morphology, the description of the physical form and external structure of plants, but since the mid-20th centu ...

, aided by the use of the

light microscope The optical microscope, also referred to as a light microscope, is a type of microscope that commonly uses visible spectrum, visible light and a system of lens (optics), lenses to generate magnified images of small objects. Optical microscopes ...

and the rise of chemistry, allowing the analysis of

secondary metabolites Secondary metabolites, also called ''specialised metabolites'', ''secondary products'', or ''natural products'', are organic compounds produced by any lifeform, e.g. bacteria, archaea, fungi, animals, or plants, which are not directly involved ...

. Currently, the strict use of

epithets An epithet (, ), also a byname, is a descriptive term (word or phrase) commonly accompanying or occurring in place of the name of a real or fictitious person, place, or thing. It is usually literally descriptive, as in Alfred the Great, Suleima ...

in botany, although regulated by international codes, is considered unpractical and outdated. The very notion of

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

, the fundamental classification unit, is often up to subjective intuition and thus can not be well defined. As a result, estimate of the total number of existing "species" (ranging from 2 million to 100 million) becomes a matter of preference. While scientists have agreed for some time that a functional and objective classification system must reflect actual evolutionary processes and genetic relationships, the technological means for creating such a system did not exist until recently. In the 1990s DNA technology saw immense progress, resulting in unprecedented accumulation of DNA sequence data from various genes present in compartments of plant cells. In 1998 a ground-breaking classification of the angiosperms (the

APG system The APG system (Angiosperm Phylogeny Group system) of plant classification is the first version of a modern, mostly molecular-based, system of plant taxonomy. Published in 1998 by the Angiosperm Phylogeny Group, it was replaced by the improved ...

) consolidated

molecular phylogenetics Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

(and especially

cladistics Cladistics ( ; from Ancient Greek 'branch') is an approach to Taxonomy (biology), biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesiz ...

or phylogenetic systematics) as the best available method. For the first time relatedness could be measured in real terms, namely similarity of the molecules comprising the genetic code.

Timeline of publications

* * * * * * * * * (In English, with list of systems since 1703 (John Ray) until 1845)

References