History of plant science

Categories: Disciplines; history of plant science

Plant Science in Antiquity

Natural philosophy, the “science” of its day, arose in Greece during the 500’s b.c.e. and included speculations about plants, such as whether domesticated plants descended from wild plants. Full-fledged science began at the Lyceum in Athens, founded by Aristotle in 335 b.c.e. Upon Artistotle’s departure from Athens in 323, his colleague Theophrastus became head of the Lyceum. He was author of two botanical treatises which cover general natural history. Historia plantarum (“Enquiry into Plants” in Enquiry into Plants and Minor Works on Odours and Weather Signs, 1916) emphasizes description of plants, their parts, and their locations, and De causis plantarum (De Causis Plantarum, 1976-1990) emphasizes physiology. The works include accounts of crops, fruit trees, and medicinal plants, but the stronger emphasis is on abstract knowledge. Greek physicians and pharmacists were more practical-minded, as is seen in Pedanius Dioscorides’ De materia medica, compiled during the first century c.e. Although it concerns medicinal plants, practically all plants had medicinal uses, and Dioscorides was the first to give a species-by-species description of the different plants known in much of the Mediterranean region.

The Romans were heavily influenced by Greek civilization, yet Romans were more practical and less abstract thinkers than the Greeks; there were no important Roman scientists. Instead of botanical treatises, Romans wrote agricultural manuals, of which the longest and most thorough was Lucius Junius Moderatus Columella’s in the early first century c.e. He used Greek sources, especially the work of Theophrastus of Eresos, and also Roman sources and his own experiences. Columella’s near contemporary, Gaius Plinius Secundus (also known as Pliny the Elder), was one of the Roman compilers of encyclopedias; he also used Greek and Roman sources, but his goal was to educate and entertain. However, that did not preclude dispensing practical knowledge. His lengthy accounts of plants emphasized useful species and included curious folklore.

Middle Ages and Renaissance

Before the western Roman Empire declined in the later 400’s c.e., original contributions to natural history were already rare. The eastern Empire persisted for another millennium, but it was politically and economically static, if not stagnant, and its main cultural contribution was to transmit Greek learning to the Arabs during the 700’s and to the Italians during the 1400’s. Arabic-language science was superior to Roman science and sometimes equal to ancient Greek science. It was studied and enlarged over a much broader geographical area than ancient science had been. Generally, Arabic-language authors did not use Roman sources, the exception being on the Iberian Peninsula, where Ibn al-?Awwam compiled his agricultural treatise during the second half of the 1100’s. Dioscorides’ manual was translated into Arabic and became the foundation of Arabic pharmacopoeias. Arabic-language science surpassed Greek science in the extent of its knowledge but rarely in theoretical understanding.

In the year 1000 c.e. both the Byzantine and Islamic civilizations were more prosperous and sophisticated than Latinized Western Europe, and yet by 1400 Western Europe had surpassed both adjacent civilizations in cultural achievements. There is no simple answer as to why Western Europe made a greater investment in higher education than any other civilization in the world, but it did so, and that investment paid off in science. While Western Europe’s culture was rather rudimentary, scholars took the opportunity to translate important works of ancient or medieval authors from Arabic or Greek into Latin and then built upon them. The most impressive botanical example was Albertus Magnus’s De vegetabilibus et plantis, written during the 1200’s without access to Theophrastus’s works but in the Lyceum tradition. Albertus used Greek and Arabic sources available in Latin translations and also Latin authors and his own experiences. However, medicine was much more important than natural history in the universities, and De materia medica was where most botanical studies focused.

During the 1450’s Johann Gutenberg developed a printing press that used movable type. It was an important step for botany and medicine because science books were prominent among early printed works. Scholars of the Italian Renaissance were enthusiastic about ancient Greek and Roman civilizations and studied living plants to decide which ancient names and descriptions fit the species they found. This concern then spread northward during the 1530’s, as seen in Euricius Cordus’s Botanologican, Otto Brunfels’s illustrated herbal, and Jean Ruel’s development of terminology to describe parts of plants. Leonhard Fuchs combined Ruel’s concern for terminology with Brunfels’s concern for illustrations in his elaborate herbal (1542). In Italy, Pier Andrea Mattioli tied the old text of Dioscorides to the new trend in illustration (1544), while in France and the Low Countries three scholars—Rembert Dodoens, Charles de L’Écluse, and Matthias L’Obel—sought new species to name and describe for their herbals. Konrad Gesner and Valerius Cordus did equally outstanding research, yet the influence of each was impaired by death before their works were fully published.

Scientific Revolution

The precise investigations contrived by Nicolaus Copernicus, Galileo Galilei, and Isaac Newton made ancient astronomy and physics obsolete, and Andreas Vesalius and William Harvey did the same for ancient anatomy and physiology. Innovations in botany were more evolutionary than revolutionary. Luca Ghini developed the botanic garden and herbarium as teaching and research aids, and his student Andrea Cesalpino wrote the first true textbook of botany (1583). Joachim Jung developed morphological terminology beyond that of Ruel and Cesalpino but without benefit of a microscope.

When the microscope became available to Robert Hooke, he described plant cells and mold fungi (1665). Following his lead during the 1670’s were Nehemiah Grew and Marcello Malpighi, who described the anatomy of plant tissues. The Dutch microscopist Antoni van Leeuwenhoek examined small plants and discovered bacteria but not bacteria’s role in disease. Cesalpino chose fruit as a key to plant classification, but Fabio Colonna decided that flowers provided a better guide to relationships. Colonna’s judgment was strengthened by the discovery of the sexuality of plants, which Grew suspected and Rudolph Jakob Camerer demonstrated. Johann Hedwig later demonstrated sexuality in bryophytes and algae but failed to understand sexuality in ferns and fungi.

The age of exploration and the scientific revolution coalesced when explorers returned to Europe with previously unknown plants. Brothers Gaspard and Jean Bauhin facilitated knowledge of the increase in known species by using binomial nomenclature in their descriptions of about six thousand species. Engelbert Kämpfer botanized in Iran and Japan, published a travel book, and brought home a herbarium that eventually reached the British Museum. John Ray traveled only in Western Europe, including Britain, but his Historia generalis plantarum (1686-1704; A Catalogue of Mr. Ray’s English Herbal, 1713) provided a synthesis of knowledge from many explorers’ observations and specimens. Joseph Pitton de Tournefort’s contributions to botany were enhanced by his explorations in the Levant, yet his main influence came from careful studies on plant genera.

In the eighteenth century the Swedish naturalist Carl Linnaeus formalized the system of binomial nomenclature and his sex-based classification system in response to all the newly discovered plants. The ease with which species could then be identified stimulated the search for still more species, which he named and classified. Some of his students, including Pehr Kalm and Carl Peter Thunberg, traveled far abroad and returned with observations and specimens. Michel Adanson explored Senegal within a French context and also devised a natural classification. John Bartram and his son William responded to European interest by discovering American plants to describe and send abroad. Joseph Banks, sailing with Captain James Cook, initiated an important partnership between British botanists and the navy, which blossomed during the 1800’s. Seeds and live plants brought back to Europe commonly were planted in botanic gardens located at universities and in capital cities, where they were accessible to botanists. Directorships of these gardens provided employment for some botanists.

Experimentation came late to botany. Edme Mariotte set a good example (1679) with his experiments in plant physiology, but his results were rather inconclusive. More successful was Stephen Hales, whose inspiration came from animal physiology; he devised methods to measure the movements of sap in vines and saplings and correlate movements with sunlight. Although his experiments were well published (1727), he had no followers, and his experiments during the later 1700’s addressed different issues. John Turberville Needham and Georges-Louis Leclerc de Buffon thought they had demonstrated spontaneous generation of life, but Lazzaro Spallanzani was skeptical and conducted superior experiments that showed they were mistaken. Spallanzani’s work inspired Jean Senebier, who translated Spallanzani’s works into French and became himself an outstanding experimentalist. Another experimental tradition arose within a chemical context, which utilized Hales’s apparatus. Chemists explored ways to generate gases and to identify them. This led Joseph Priestley, Horace Bénédict de Saussure, and Jan Ingenhousz to conduct experiments on live plants in glass enclosures during the 1770’s. Camerer (1694) and Josef Gottlieb Kölreuter in the later 1700’s were among the early experimenters on sexual reproduction in flowers.

Taxonomic Botany

Taxonomic botany, as formally organized by Linnaeus, became the main scientific specialty during the 1800’s because many new species were still being discovered in all parts of the world. Outstanding collectors included Alexander von Humboldt, Robert Brown, Joseph Dalton Hooker, George Englemann, and Edward Lee Greene. The accumulation of herbaria specimens and plantings in botanic gardens enabled botanists to produce encyclopedic accounts of species, such as those by Augustin Pyramus de Candolle and his son Alphonse Louis de Candolle and by George Bentham and Hooker.

Phytogeography

Phytogeography developed using those same plant collections and taxonomic encyclopedias. Linnaeus had begun writing on this subject, and Karl Ludwig Willdenow, who trained Humboldt, carried it further. However, Humboldt’s extensive explorations, collections, environmental measurements, and scientific publications became the real foundation of phytogeography (1808). In 1820, Augustin de Candolle introduced the concept of competition among species as a factor in the distribution of species, and his son Alphonse de Candolle wrote an important synthesis of phytogeography, Géographie botanique raisonée (1855, 2 volumes). August Heinrich Rudolph Grisebach achieved another world synthesis in 1872. Hewett Cottrell Watson founded British phytogeography (1835) and devoted his career to a study of the distribution of all British species and their variability. Asa Gray, an American who specialized in taxonomic botany, became, through his association with Joseph Hooker and Charles Darwin, the United States’ leading phytogeographer.

Evolution and Heredity

Ideas on the evolution of species made little headway until the French Revolution (1789); then two naturalists wrote books discussing it in plants and animals. Although the British became enemies of the Revolution, Erasmus Darwin favored it. Both he and Jean-Baptiste Lamarck published speculative hypotheses that viewed struggle as a source of new traits, to be followed by the inheritance of the new traits. Johann Wolfgang von Goethe speculated in a more idealistic way about species varying from a basic type.

Paleobotany was less popular than vertebrate paleontology, but Alexandre and Adolphe-Théodore Brongniart, father and son, made important discoveries. Franz Unger followed in their footsteps. It became obvious to them that fossil species differed from living species, causing Unger to speculate on changes in species. Charles Darwin, who read his grandfather’s books, outdid Erasmus Darwin with a carefully developed theory of evolution by natural selection. Alfred Russel Wallace had read many of the same scientific works as Charles Darwin, and he had also read Darwin’s Journal of Researches (1839) before publishing his own ideas on evolution that resembled Darwin’s theory of natural selection. That theory remained controversial for decades after its publication in Darwin’s On the Origin of Species by Means of Natural Selection (1859), but it also stimulated much study of both fossil and living species to discover the details of evolution. Charles Edwin Bessey took up the challenge of explaining the history of plant evolution.

Heredity was a weak link in Darwin’s theory of evolution, awaiting the advent of genetics. Karl Gärtner conducted numerous empirical studies but without achieving a theoretical breakthrough. When Gregor Mendel, an inconspicuous monk, developed experiments on peas which clarified patterns of inheritance, his thinking was beyond his audience’s comprehension, including Karl Wilhelm von Nägeli, to whom he turned for encouragement. Mendel’s 1866 article was only appreciated in 1900, when three botanists—Karl Franz Joseph Erich Correns, Erich Tschermak, and Hugo de Vries—independently rediscovered it and Mendel’s laws. Meanwhile, others followed cell division more and more closely, demonstrating that chromosomes carry hereditary material (genes) and that those chromosomes divide in a regular way during both mitosis and meiosis.

Cytology, Fertilization, and Alternation of Generations

Studies on cytology, fertilization, and alternation of generations advanced considerably during the 1800’s because advances in the quality of microscopes and slide-preparation techniques allowed botanists to achieve a more precise understanding than had been possible earlier. Charles-François Brisseau de Mirbel initiated French cytology with studies on plant anatomy, seeds, and embryos (1800-1832). Brown used a microscope to discover the cell nucleus. Matthias Jakob Schleiden, who used the improved microscopes, is credited with establishing the cell theory in plants—after his colleague. Theodor Schwann had done so for animals, though Schleiden misunderstood cell division. Nevertheless, his botany textbook (1942-1943) inspired others to investigate cellular processes. Hugo von Mohl advanced microscopy and developed the protoplasm concept. Wilhelm Friedrich Benedict Hofmeister and Nathanael Pringsheim studied fertilization and alternation of generations in diverse groups of plants. Later, Walther Flemming and Eduard Adolf Strasburger used improved techniques to study chromosomes during mitosis and meiosis.

Microbiology and Mycology

Microbiology and mycology also benefited from advances in microscopy and cytology. Ferdinand Julius Cohn, Anton de Bary, and Louis Pasteur all made their main contributions during the 1850’s, 1860’s, and 1870’s. Cohn studied unicellular algae and bacteria. De Bary founded mycology with studies on sexual reproduction in fungi and on the two-stage life cycle of wheat rust. Pasteur vindicated Schwann’s claim that alcohol fermentation is caused by yeast and discovered anaerobic metabolism. Pasteur also investigated the causes of various diseases, several of which were bacterial. Robert Koch developed bacteriological techniques that enabled him to demonstrate clearly the bacterial cause of several diseases.

Physiology and Agronomy

Physiology and agronomy received less attention than several other botanical specialties during the first half of the nineteenth century, though Henri Dutrochet showed that plant respiration and animal respiration are essentially the same. In the second half of the century, Julius von Sachs and John Bennet Lawes made these specialties more conspicuous. Sachs was a brilliant experimentalist, teacher, and author of textbooks, making him the founder of modern plant physiology. Lawes used private resources to found modern agricultural research in Britain at a time when the U.S. Congress was establishing land grant colleges and state agricultural and forestry research stations. By the end of the century, American scientists were doing as much or more agricultural research as the rest of the world combined. Vasily Vasilievich Dokuchaev developed soil science (agronomy) as an aid to Russian agriculture.

Twentieth Century

All of the specialties from the 1800’s continued throughout the 1900’s. In addition, genetics, ecology, and molecular biology became important specialties. Plant sciences advanced at an unprecedented rate and in more countries than ever before.

Evolution became the organizing theory for all of biology. However, evolutionary biology retained a close relationship with taxonomy and phytogeography. Bessey, and later John Hutchinson, advanced the understanding of the evolution of vascular plants as a whole, while Marie Stopes contributed paleobotanical evidence. Two Russians took the lead in their subspecialties: Nikolai Ivanovich Vavilov used genetics and cytological evidence to clarify the history and phytogeography of domesticated plants, and Aleksandr Ivanovich Oparin used physiology and biochemistry to investigate the origin of life.

Genetics did not develop within a strong evolutionary context during its first four decades, though de Vries had an evolutionary motive to study heredity and Wilhelm Ludwig Johannsen’s studies on breeding homozygous versus heterozygous strains of peas had evolutionary implications. Genetics was advanced by both botanists and zoologists. The three re-discoverers of Mendel’s laws and article were botanists. Thomas Hunt Morgan studied gene linkage on chromosomes using fruit flies, and later Barbara McClintock continued these studies using maize. Albert Francis Blakeslee initially studied sexual fusion in fungi but is remembered more for discovering that colchicine produces polyploidy in plant chromosomes. A new specialty, molecular biology, arose out of James Watson’s and Francis Crick’s struggle to understand the structure and function of the gene, as represented by deoxyribonucleic acid (DNA).

Four English botanists advanced plant anatomy, particularly at the level of cellular biology. Ethel Sargent studied intracellular structures relating to cell division and vascular bundles as clues to evolution. Vernon Herbert Blackman studied plant cytology and alternation of generations in rust fungi. Agnes Robertson Arber wrote monographs on monocotyledons as a whole and on particular groups of them. Irene Manton used an electron microscope to study chromosomes and cell organelles. An Italian animal histologist, Camillo Golgi, discovered the “Golgi body” within an owl’s brain cell (1898), but explanation of its function came much later. Christian De Duve was a Belgian cytologist and biochemist who used a centrifuge and electron microscope in his research to discover new organelles: lysosomes and peroxisomes.

Physiology flourished during the 1900’s, beginning with Frederick Frost Blackman’s studies on respiration, Jagadis Chandra Bose’s on biophysics, and Mikhail Semenovich Tsvet’s on cytophysiology. In the 1930’s Paul Jackson Kramer began investigating water usage, and Hans Adolf Krebs began investigating cyclic metabolic pathways. After World War II, François Jacob studied the functioning of DNA and RNA, the genetic control of enzymes, and helped develop the concept of the operon in cellular physiology. Melvin Calvin took advantage of availability of radioactive tracers, particularly carbon 14, to clarify biochemical steps in photosynthesis.

Ecology arose simultaneously with genetics but at a slower pace. Johannes Warming, Gottlieb Haberlandt, and Andreas Franz Wilhelm Schimper were botanists who laid a foundation for plant ecology shortly before 1900, and the self-consciously ecological researches by Christen Raunkiaer, Felix Eugen Fritsch, Frederic Edward Clements, and Henry Chandler Cowles built upon their foundation. Fritsch studied periodicity in phytoplankton and helped found the Freshwater Biological Association. Andrew Ellicott Douglass was interested in sunspot cycles, and to document their occurrence he developed dendrochronology, which also was used to clarify vegetation cycles. Clements was an enthusiastic theoretician; Cowles was more cautious, and Henry Allan Gleason and Arthur George Tansley attacked Clements’s concepts of climatic climax and plant communities as overinterpretations of the evidence. Gleason preferred the concept of association, which John Thomas Curtis modified into the continuum. Tansley, who helped found the British Ecological Society and the Journal of Ecology, preferred his own ecosystem concept, which became extremely important after World War II. Early examples of the use of ecological concepts for environmental protection are Paul Bigelow Sears’s Deserts on the March (1935) and Rachel Carson’s Silent Spring (1962).

Microbiology expanded beyond what can be indicated here. Five virologists illustrate the involvement of plant scientists in microbiology. Dmitri Iosifovich Ivanovsky investigated tobacco mosaic disease in the 1890’s and early 1900’s and found evidence that the causative pathogen passed through a porcelain filter. His microscopic observations were excellent, yet he concluded that the pathogen was a bacterium, whereas it was later determined to be a virus. Martinus Willem Beijerinck investigated the puzzle and found the pathogen is not a toxin and could not be cultivated in vitro; he concluded it must be a molecular pathogen. Three other filterable pathogens were also identified in the same period. Later, Louis Otto Kunkel studied viral diseases in potatoes and sugarcane in order to inhibit their transmission. Frederick Charles Bawden and N. W. Pirie discovered that plant viruses are nucleoproteins.

Agronomy benefited enormously from the advance of many sciences, as indicated by the work of four plant scientists. George Washington Carver drew upon chemistry to find new uses for peanuts and sweet potatoes. Rowland Harry Biffen used the new genetics to improve crops, including rust-resistant wheat. Vavilov used genetic variability in wild plant populations to modify closely related domesticates to achieve varieties best suited to the Soviet Union’s diverse environments. Norman E. Borlaug, known as the father of the Green Revolution, bred varieties of rice, corn, and wheat that greatly increased yields in tropical countries.

Bibliography

Ainsworth, Geoffrey C. Introduction to the History of Mycology. New York: Cambridge University Press, 1976.

‗‗‗‗‗‗‗. Introduction to the History of Plant Pathology. New York: Cambridge University Press, 1981. Well-illustrated topical surveys, with contemporary portraits and plant illustrations, notes, and bibliographies.

Greene, Edward Lee. Landmarks of Botanical History. 2 vols. Edited by Frank N. Egerton. Stanford, Calif.: Stanford University Press, 1983. A detailed survey of major works from antiquity to about 1700; editor added three appendices to fill gaps in coverage. Includes contemporary portraits and plant illustrations, extensive bibliography.

Hessenbruch, Arne, ed. Reader’s Guide to the History of Science. London: Fitzroy Dearborn, 2000. Includes discussions and bibliographies on a several developments in the history of botany. Index.

Morton, A. G. History of Botanical Science: An Account of the Development of Botany from Ancient Times to the Present Day. New York: Academic Press, 1981. Concise and well balanced. A few contemporary portraits and illustrations, notes.

Stafleu, Frans A., and Richard S. Cowan. Taxonomic Literature: A Selective Guide to Botanical Publications and Collections with Dates, Commentaries and Types. 2d ed. 8 vols. Utrecht, Netherlands: Bohn, Scheltema and Holkema, 1976-1992. A vast encyclopedia that is essential for the history of taxonomic botany. Coverage is from about 1500 to recent times.

Waterson, A. P., and Lise Wilkinson. An Introduction to the History of Virology. New York: Cambridge University Press, 1978. A topical survey with some contemporary portraits and illustrations, notes, and bibliography.