A Look at the History of Plant Classification

I. Important Influences on Classification Systems

II. The Ancients

We will not have time to cover this period.  If you are interested, here are my notes!

III. The Pre-Linnaean Period.

A. Andrea Caesalpino [name sometimes Latinized as Andreas Caesalpinus] (1519 to 1603). Wikipedia here.

B. Joseph P. de Tournefort (1656 to 1708). Wikipedia here.

C. John Ray (1627 to1705). Wikipedia here.

1. A British botanist who wrote under the name of John Wray. He was a true academic, lecturing in Greek, mathematics, the humanities and he became praelector, junior dean, and college steward as well as preaching the gospel.

2.  His most famous works:

3. Plants that looked alike were grouped together, thus this is considered a natural system.  But he used a complicated system of classification that used many different characters, split natural groups, and lumped together unnatural ones. He believed in "essential" characters. He coined the word "species".

IV. The Linnaean Period.

A. By middle of 18th Century, people needed an easy, rapid way to identify and name plants. People traveled widely owing to advances in navigation.  The groundwork was laid by the herbalists, Bauhin, de Tournefort, and Ray with their natural systems of classification.  Technologically, there were early microscopes, use of herbarium specimens, and printed books were now available to the masses.  Thus, these many developments made the science of botany ready for a person to synthesize all the information.

B. Carl von Linné (Latinized to Carolus Linnaeus). (1707 to1778). Wikipedia here.

1. Early life. Son of a Swedish parson, Linnaeus was born in Råshult, Sweden, May 22, 1707 (home). Father was a naturalist/botanist, may have instilled this in young Carl. He lost interest in formal schooling and was tutored. At age 17 he enrolled in secondary school to prepare for the ministry. He did well in some subjects (mathematics, physics, botany!) but poorly in others (languages and theology). His teachers suggested he consider a profession other than the ministry, but noted he was a botanical genus! [L in his room]

2. One of his teachers, the family physician Johan Rothman, privately tutored Carl in physiology and botany. Remember, at that time most botanists were physicians, but physicians were considered akin to barbers in the social hierarchy. Carl learned of Vaillant's "Sermo de Structurea Florum" (1718). Discussed sexual reproduction in plants - probably influenced his later work. Following the tutoring, he received his certificate (diploma).

3. At age 20 Carl entered the University of Lund, then was educated in Uppsala - the most prestigious university in Sweden. He studied under Dr. Olof Rudbeck. Linnaeus cataloged the plants of the Uppsala Botanical Garden. His student paper "Praeludia Sponsaliorum Plantarum" had to do with the sexuality of plants.

"The actual petals of a flower contribute nothing to generation, serving only as the bridal bed which the great Creator has so gloriously prepared, adorned with such precious bedcurtains, and perfumed with so many sweet scents in order that the bridegroom and bride may therein celebrate their nuptuals with the greater solemnity."

4. Lapland JourneyLinnaeus wanted to explore the Lapland frontier so he organized a trip in 1732. Got financial support through the Royal Society of Sweden. Trip resulted in the Flora of Lapland and strongly influenced L - "one of the most fruitful seasons of his whole life" (autobiography - refers to self in 3rd person). During his trip (L in costume), he collected 537 specimens including one he called Campanula serpyllifolia. This was later named by a Dutch botanist, J. F. Gronovius as Linnaea borealis (Campanulaceae or Linnaeaceae) with these words attached:

"... a plant of Lapland, lowly, insignificant, disregarded, flowering
but for a brief space - from Linnaeus who resembles it."

5. Linnaeus had to get his degree since his marriage to Sara Elizabeth Moraea (daughter of a wealthy businessman) was contingent upon it. So, he went to the University of Harderwijk in the Netherlands - a "real diploma mill" and defended his previously written dissertation only ten days after arriving in Holland!

6. Linnaeus met George Clifford III, director of the Dutch East India Company - very wealthy. He hired L. as his personal physician at Hartekamp. Linnaeus was treated like a king - expense accounts for research and travel, private apartment, servants, etc. During this time he published Hortus Cliffortianus (plate from this work) (full text here), traveled, and became famous. His "Systema Naturae" which laid the foundation for his later works, was published while at Hartekamp. Later he got his M.D. degree.

7. Badgered by Sara Moraea and her father to return home, L. traveled back to Sweden and in 1739 married Sara (L. wedding picture, holding Linnaea!). He set up his own medical practice specializing in treating venereal diseases! He rose in the ranks and was eventually elevated to nobility by the king - now used the name von Linné. He gave up his medical practice to become a professor at Uppsala. Many of his students traveled the world returning plants for him. His field trips were quite ostentatious - involved marching bands, huge crowds of people, picnics, etc. L. is remembered for his ability to popularize nature as much as for his contribution to nomenclature.

8. His classification system is called artificial because it relied upon a few features of the flower (mainly the number of stamens and pistils) as the primary basis for division (page out of Systema). He himself knew it was artificial - suggested it would be a long time before anyone knew enough about nature to devise an entirely natural taxonomy. His system was correct in some cases, but not in other (put clearly unrelated plants together).

9. From his earlier experiences, he probably became a bit obcessed with sex in plants. He developed the Sexual System of classification. He called it his Nuptiae Plantarum (marriages of plants). Written in metaphorical terms in Systema Naturae "husband and wife have same bed," or "five husbands in the same marriage," etc. referring to the arrangement of stamens and carpels in the flower. It got a bit explicit, e.g. "husbands live with wives and concubines" or "equal polygamy consists of many marriages with promiscuous intercourse." Johann Siegesbeck (one of L.'s critics) said that such

"loathsome harlotry as several males with one female would not be
 permitted in the vegetable kingdom by the Creator!"

He also said:

"Who would have thought that bluebells and lilies and onions could
be up to such immorality? How could so licentious a method be taught
 to the young without offense?"

The Reverend Samuel Goodenough, Bishop of Carlisle wrote:

"A literal translation of the first principles of Linnaean botany is enough to shock female modesty. It is possible that many virtuous students might not be able to make out the similitude of Clitoria"

Linnaeus got back at his detractors - for example, he named a nondescript weed (Siegesbeckia orientalis) after Siegesbeck! Although it caused people of the time to gossip, the system was simple so the appeal of the "Sexual System" was instananeous. The system involved counting the number of stamens (which gave the Class) and the number of pistils (gave the Order). So, Canna with one stamen and one pistil was classified in Class Monandria order Monogynia.

10. Linnaeus believed in a fixed number of species on earth, placed here by the Creator. He also believed he was the "chosen one" to classify these organisms (Temple of Flora, Thornston). "God creates, Linnaeus arranges". In one of his five autobiographies, he writes (with himself as third person again):

"God Himself guided him with His own almighty hand. He caused him to see more of creation than any other mortal before him. He bestowed on him the greatest insight into natural history, greater than any other had ever received."

11. He was incredibly prolific (or his students were who sent specimens for naming). Named 12,000 species (7.700 plants, 4,300 animals). 1,105 genera named by him. His most important works were:

12. Linnaeus is most known today for the following reasons:

C. At Missouri Botanical Garden in St. Louis there is the Linnaeus house and a sculpture of him outside the Lehman Herbarium.

V. Post-Linnaean Period

A. The French never really adopted the system of Linnaeus because they had experience in the botanical gardens (e.g. Jardin de Plantes de Paris). They developed the first natural system of classification. Some leading botanists of that time were:

1. Michel Adanson (1727 to1806). Wikipeda hereFamilles des Plantes. Experience in Africa forced him to develop ways to logically deal with large numbers of characters. His methodology foreshadowed numerical taxonomy (phenetics). Did not believe in essential characters but that all the characters taken together should be used in a classification.

2. Antoine L. de Jussieu (1748 to1836). Wikipedia here. Genera Plantarum. Family of 4 de Jussieu's. Jussieu constructed his groups synthesis, successively building up genera, families, etc. based on overall similarity. He did believe in essential characters and did not believe there were sharp delimitations between groups - all groups were connected with continuous variation between.

The Jardin des Plantes (in Paris) was arranged such that similar plants were placed in the same beds (photo of a composite bed, Hamilton, Ontario). This was an attempt to reflect a Natural Classification system, i.e. one based ideas (or one person or many) of relationships. Many of the families recognized then are still recognized today. Botanists of time readily accepted this system (over that of Linnaeus).

3. Jean Baptist de Lamarck (1744 to1829).Wikipedia here. Flore Françoise. Best known for an early theory of evolution by inheritance of acquired traits. Flore Françoise used identification keys similar to dichotomous keys of today. Also came up with the first numerical weighting scheme for characters based upon frequency of distribution among plants.

4. Augustin Pyramus de Candolle (1778 to 1841).Wikipedia here. Prodromus Systematis and Naturalis Regni Vegetabilis. Family of 3, Swiss, Prodromus was an attempt to do a world flora (the last attempt), never finished, 58,000 species, 161 families. Depicted the catkin-bearing dicots (e.g. Betulaceae, Fagaceae, etc.) as being related to gymnosperms. Began the dicots with Ranunculaceae. De Candolle believed there were sharp discontinuities in nature (opposite of de Jussieu).

B. Evolutionary Classifications.

1. Charles Darwin (1809 to 1882). Wikipedia here. On the Origin of Species by Means of Natural Selection (1859). Darwin strongly influenced by observations during the voyage of the H.M.S. Beagle to the Galapagos Islands. Observed differences in animals (e.g. finches) and plants on different islands prompted his mechanism for evolutionary change, i.e. natural selection. Prior to his trip, Darwin was strongly influenced by Charles Lyell, a geologist, who proposed a theory of geological gradualism (slow, continuous changes produced features we see today). Darwin thought then that the earth was much older than 6000 years and that evolutionary change occurs through gradual, accumulated differences. Keep in mind that the work of Mendel was not yet common scientific knowledge, hence the genetic mechanism for such change (mutation) was not linked to these ideas. After his Galapagos trip, he wrote Origin of Species in Down House, Kent, UK. Influential people such as Lyell and Hooker have their pictures displayed in Darwin's house. At the same time as Darwin Alfred R. Wallace was working in the East Indies and developed a very similar theory. Both theories were presented at the meetings of the London Linnaean Society in 1858. 

Darwin did not discuss how to rank organisms (in other words, put them in genera, families, etc.), but he did understand the hierarchical nature of groups.  Indeed, the only figure shown in Darwin's Origin is a phylogenetic tree.  The concept of evolutionary change was embraced by most scientists, including Haekel whose "Tree of Life" (1866) depicted all taxa (Protists, Plants, and Animals).

2. George Bentham (1800 to 1884) and Sir Joseph D. Hooker (1817 to 1911). Wikipedia for GB here and JH here. Genera Plantarum. Worked at Kew Botanic Gardens, near London. Hooker was a friend of Darwin and provided him a new understanding of plant distributions. Genera Plantarum was published after Darwin's Origin of Species, but it was not possible to change system to reflect new evolutionary concepts despite the fact that both B & H were great champions of this theory. Named 200 families and 7,569 genera, with fabulously detailed, often original descriptions. Many herbaria in world are still arranged according to system. He recognized monocots and dicots and began the latter with the polypetalous plants.

C. Phylogenetic Classifications

1. Asa Gray (1810 to 1888). Wikipedia here.  Not a major figure in systems of classification, but first professor of botany at U.S. university (Harvard, 1842). Gray corresponded with Darwin and, as did Hooker, influenced his thinking. See this webpage for more on the Gray-Darwin connection. Most famous work: A Manual of Botany of the Northern United States (1848). Harvard became leading taxonomic botanical institution in U.S. Gray's Manual of Botany published later by M. L. Fernald (8th. edition 1950). Photo of Gray with plant press.

2. Adolf Engler (1844 to1930) and Karl A. E. Prantl (1849 to 1893). Wikipedia for AE here and KP here.  First phylogenetic systems were developed at the Botanical Garden in Berlin (photos 1, 2, 3). Engler and Prantl believed that the classification system should reflect the evolutionary history. Their greatest work: Die Natürlichen Pflanzenfamilien, contained marvelous, detailed illustrations, as shown by this page. Their philosophy of evolution was that simple structures gave rise to more complex ones.  Because they saw gymnosperms preceding angiosperms, they thought the most primitive angiosperms were those with cone-like, unisexual inflorescences (catkins) such as alder (Alnus) and birch (Betula). This was the first major Phylogenetic Classification. Voluminous publishers! Dominated taxonomic botany at turn of 20th. Century. Their system is used today to arrange plants in herbaria and floras.  Although very useful for this purpose, their concepts of what is primitive and advanced are not followed today.  

3. Charles Bessey (1845 to 1915). Wikipedia here. Student of Asa Gray, went to Iowa State, then Nebraska. He developed a set of "dicta" (rules) stating which characters were primitive and which were advanced in flowering plants. Not all considered correct today but many are (as Cronquist said, "we are all Besseyans"). The Magnolia type flower was considered primitive, not the unisexual catkin-bearing plants of Engler and Prantl. Published in 1915: The Phylogenetic Taxonomy of Flowering Plants -- relationships depicted as "Bessey's Cactus."

4. Robert F. Thorne (1920 to present ). Works at Rancho Santa Anna Botanical Garden in Claremont, CA. A Phylogenetic Classification of the Angiospermae is his system of classification.

5. Armen Takhtajan (1910 to present). Wikipedia here. Was at Lenningrad, now spends most time at NY Bot. Garden. Flowering Plants: Origin and Dispersal was an influencial early work. A revision of this classification appeared in 1997: Diversity and Classification of Flowering Plants.

6. Rolf Dahlgren (1932 to 1985). University of Copenhagen. A Revised System of Classification of the Angiosperms here. Depicted relationships with "Dahlgrenograms". 

7. Arthur Cronquist (1919 to 1991). Wikipedia here. Worked most of his life at the New York Botanical Garden. Many of his ideas are Besseyan with some influence from Takhtajan. His most famous work: An Integrated System of Classification of Flowering Plants (1981) and the revision in 1988, were very influential.  The major groups of angiosperms were divided into six subclasses.

8. Modern Phylogeneticists. The term Molecular Phylogenetics is the study of evolutionary relationships among organisms using DNA and RNA. A tree is constructed using DNA sequences and the organism relationships are inferred from that tree. Your textbook is based entirely on the existing knowledge about the phylogeny of all plant groups covered.  For angiosperms, the classification generally follows the APG (Angiosperm Phylogeny Group) and APG2 system.

Summary of Approaches to Classification

Utilitarian (Uses)    Dioscorides, Herbalists

Form (habit of plant) Theophrastus, Caesalpino

Artificial (few obvious characters) Tournefort, Linnaeus

Natural (overall resemblances) Bauhin, Ray, de Jussieu, de Candolle, Bentham & Hooker

Phylogenetic (pre-molecular, intuitive evolutionary ideas) Engler & Prantl, Bessey, Hutchinson, Cronquist, Takhtajan, Thorne, Dahlgren

Phylogenetic (molecular, evolutionary) APG I, II, III

Links to Linnaeus

Linnaeus at 300. A series of articles in Nature commemorating his 300th. birthday.

Linné Online. From Uppsala University.

Linnaeus from Wikipedia.

Carl Linnaeus. From Berkeley Evolution pages.

The Compleat Naturalist by Wilfred Blunt. This Google book shows many of the 272 pages!

Linnaeus. From Strange Science.

Carl Linnaeus Botanical History. From the Department of Phanerogamic Botany, Swedish Museum of Natural History.

Carl Linnaeus. From the Linnean Society of London.

SIUC / College of Science / Elements of Plant Systematics
URL: http://www.plantbiology.siu.edu/PLB304/HistTaxon.html
Last updated: 6-Jan-13 / dln