Botany

BOTANY (from Greek botane—herb), a science having as its task the comprehensive study of plants. Main stages of development. Botany arose as a purely descriptive science in connection with practical demands, especially in the field of agriculture and medicine. Already in the works of authors of antiquity (Hippocrates, Theophrastus) one finds the enumeration and partly the description of several hundred plants with attention given to their medicinal properties. In Dioscorides (1st century A.D.), the very title of his work—"Materia medica"—speaks for itself. It contains an enumeration of about 600 plants, to which medicinal properties are attributed. After stagnation in the Middle Ages, botany was reborn in the 16th century in Germany, where so-called "herbals" (Kräuterbücher) began to appear at this time, containing descriptions of plants with an indication of their use in medicine. In general, "hortus botanicus" and "hortus sanitatis" at the time of the "herbals" were inseparable from one another. Further descriptions of new plants, local and foreign, in connection with the geographical discoveries of the 16th–17th centuries, necessitated the classification of the accumulated material, which led to the development of a plant system. This classificatory trend received its highest expression in C. Linnaeus (Linné, 1707–1778). The main merit of Linnaeus lies not so much in the fact that he introduced any new thoughts and trends into botany, but in the fact that he put the old accumulated material in order. The most important things here are: 1) the introduction of the so-called binary nomenclature, i.e., the naming of each plant with two words (Latin), of which one—a noun—denotes the genus, and the other—a definition for it—denotes the species (the very concepts of "genus" and "species" were known long before Linnaeus); 2) the creation of the so-called "sexual" system of plants. In essence, this is a purely artificial grouping of plants based on one arbitrarily chosen trait—the number of stamens in the flower; in this respect, it represents rather a step backward compared to earlier botanists (e.g., Cesalpino, 1519–1603). However, thanks to its artificiality, the Linnaean system is distinguished by great clarity, which created its great popularity. Furthermore, one should note the enormous authority of Linnaeus as a connoisseur of plant forms, and the fact that in his works it was established for the first time with complete clarity that the systematic units (species) adopted by him represent something real. The influence of Linnaeus on his contemporaries and on the further development of botany was exceptional: a universal fascination with collecting, drying, and cataloging plants ensued; botany received the characteristic name—scientia amabilis. At the same time, within botany itself, the descriptive systematic trend secured for itself an almost exclusive dominance for a long time, so that only by the end of the 18th–beginning of the 19th century did other branches of botany begin to develop alongside systematics. The further development of systematics after Linnaeus is characterized, mainly, by attempts at such a classification of plants that would take into account a number of their traits and reflect the actual relationships between individual groups (natural systems replacing the Linnaean artificial system). Here one should note the significance of the idea of evolution, which spread in botany in the second half of the 19th century along with the teachings of Darwin. The evolutionary idea is a necessary logical justification for a natural system and allows replacing the vague notion of the old authors about "affinity" between groups of plants with a completely clear concept of their blood relationship. The study of the microscopic structure of plants began in 1671 with the works of the Italian Malpighi and the Englishman Grew (Malpighi, Grew). However, these "fathers" of plant anatomy (histology) remained without followers for a long time; only at the beginning of the 19th century did microscopic study appear on the scene again (Mirbel, Moldenhawer). The middle of the 19th century is characterized by a particularly brilliant development of this trend. Shortly before this, the cellular structure of plants and the origin of cells had been definitively clarified (Schleiden, Nägeli, and others; 1838 and subsequent years), and then, by a number of scientists, plant anatomy was placed on the path along which it has been moving to the present time. Simultaneously with the study of the structure of the adult plant, the study of the history of development proceeded. Here one should especially note the classic studies of Hofmeister (Hofmeister, 1849–51 and subsequent), which clarified such most important moments in the development of plants as the alternation of generations, and erased the sharp boundary between phanerogams and cryptogams. A continuation of these studies in more recent times are, on the one hand, the works of Gorozhankin, 1880, and Belyaev, 1885 and subsequent (development and fertilization of gymnosperms and heterosporous pteridophytes), and on the other—the works of the Japanese Ikeno, 1898, and Hirase, 1896 (discovery of spermatozoa in gymnosperms), and Navashin, 1898 (double fertilization in angiosperms). The same microscopic method in the middle of the 19th century yielded brilliant results in the study of lower spore plants. Through the works of Nägeli, Thuret, de Bary, Voronin, Tsenkovsky, Pringsheim, and others, a number of questions were clarified here, the significance of which goes far beyond the limits of spore plants themselves. Such are: the doctrine of the cell and its main structural elements, the essence of fertilization as the fusion of two sex cells (Thuret, 1851, in the alga Fucus), and others. The development of physiological knowledge proceeded under the influence of other methods. Here, physical-chemical methods, experiment, and precise quantitative accounting of the results of the experiment performed play the most important role. Therefore, plant physiology developed, following in the footsteps of physics and chemistry, and often not even botanists, but physicists and chemists played the leading role here. The first true physiological study of this kind is the work of the Englishman Hales (1727) on the movement of sap in plants; in it, the author, a physicist by profession, by means of a well-developed methodology, determines root pressure, quantitatively studies evaporation, etc. If the physicist Hales laid the foundation for physical plant physiology, then the chemist Priestley and the physician Ingenhousz at the very end of the 18th century founded chemical physiology, discovering the plant's absorption of CO₂ and the release of O₂. This most important aspect of plant nutrition was then studied in more detail in the works of Saussure (1804), Boussingault (middle of the 19th century), Sachs, K. A. Timiryazev (70s–90s of the 19th century), and others. The successes of organic chemistry in the middle of the 19th century made it possible to study the transformation of substances in the plant (Boussingault, Meyer, Sachs, Pfeffer, Dyakonov, Palladin, and others). The entry of substances into the plant cell was studied first by the physicist Dutrochet (1830), who discovered the phenomena of osmosis, but then W. Pfeffer (1877) and de Vries (1884), who studied these processes in more detail, established such general regularities that they created an entire chapter of physical chemistry (a rare case when physiology was ahead of physics and chemistry). In general, among external factors, the development of botany was determined by two main influences; on the one hand, the development of neighboring scientific disciplines, both biological and physical-chemical, and the improvement of their methods, and on the other hand, the demands of practical life exerted a great influence on botany. Thus, plant physiology developed in close connection with agronomy. The demands of medicine and the study of medicinal plants also influenced the development of almost all branches of botany and even contributed to the development of some special methods, e.g., microscopic and microchemical analyses of plant products. If previously the real workers in the field of botany were often physicians, now this connection between botany and medicine is emphasized by the circumstance that almost half of the research on plant anatomy and biological chemistry is performed by pharmacists. Current state and branches of botany. Already from the historical outline, three main branches of botany are clearly revealed: 1) systematics, 2) morphology, 3) physiology. I. Modern systematics has as its main goal to clarify the origin and relationship of plant groups and, as a final result, to illuminate the evolution of the plant world as a whole. For these purposes, it uses data from almost all other botanical disciplines, morphological and physiological, in particular, biochemistry. The latter has received particularly important significance in the works of Mez and his school; they use, for establishing the relationship between different plants, the so-called precipitin reaction of precipitation in the serum of appropriately immunized animals (see Serodiagnostics). Among other major modern systematists, one should point out Engler, Wettstein, Hallier. Their systems differ significantly from each other and from the system of Mez.

The main task of taxonomy has still not been reached by far. In addition to the indicated main scientific task, plant taxonomy has another, more specific, but also very important one: to present in an easily viewable form all that huge material on the description of individual plants, which is becoming ever more extensive, as can be seen if only from the fact that Dioscorides knew 600 species of plants, Linnaeus 8,000, and at the present time about 300,000 have been described. Methodologically, phytopaleontology, which studies the plants of previous geological epochs, and phytogeography, which studies the distribution of plants over the surface of the earth, are closely adjacent to taxonomy. The position of so-called phytosociology is less definite. This young branch, which arose already in the 20th century, has as its task the study of natural groupings of plants, i.e., communities. By studying the relationships that take place between members of a community and between entire communities, as well as their relationships with the surrounding environment, phytosociology has the signs of a physiological discipline (in particular, it draws closer to ecology), but, on the other hand, it clarifies the laws of the distribution of communities over the surface of the earth, and therefore its connection with phytogeography is especially close. Phytogeography and the phytosociology adjacent to it are cultivated now, predominantly, in sparsely populated countries, where much untouched nature still remains, for example, in Sweden, Switzerland. In the USSR, these departments currently attract, perhaps, no less than half of all botanists. II. Morphology has as its goal the study of the structure of a plant. It is currently divided into: 1) morphology proper, which studies the laws of external structure; 2) embryology, which studies individual development; 3) anatomy, which studies the internal microscopic structure of a plant; from anatomy, 4) cytology, which has as its task the study of the plant cell, has separated as a special branch. At the present time, the embryological-cytological direction predominates in plant morphology, especially in connection with genetics (see). Plant anatomy is also being developed quite diligently. As for morphology proper as the study of the external form of a plant, this department has now already significantly exhausted itself, but on the other hand, a new branch is now developing—experimental morphology, which studies the influence of the external environment on the form and development of a plant. This department occupies an intermediate position between morphology and physiology. It is based on the remarkable research of Bonnier and especially Klebs (Bonnier, 1894; Klebs, 1896). III. Plant physiology is divided into: 1) chemical physiology (study of metabolism in a plant) and 2) physical physiology (study of growth phenomena and other manifestations of physical forces in a plant). The former has the predominant importance at the present time, which is to a significant degree explained by the requirements of applied disciplines—agronomy and pharmacy, for which this department of plant physiology has especially great importance. The following occupy a less definite position: 1. Plant ecology. This young department of botany, founded by the works of Schimper and Warming at the end of the 19th century, is engaged in the study of the relationships that exist between a plant and its natural environment, the study of what features of organization allow a given plant to exist in a given environment. From this, the connection of ecology with physiology, on the one hand, and with phytogeography, on the other, is clear. That is why the content of this, still developing, branch is interpreted differently: sometimes as a kind of field physiology, sometimes as a part of phytogeography, under the name of ecological geography. 2. Phytopathology. As a discipline studying disease processes in plants, phytopathology is close to physiology. However, its modern content is reduced not so much to the study of physiological processes in a sick plant as to the clarification of anatomical changes (pathological anatomy) and the study of those parasites, mostly fungi, which cause a given disease. From this, the connection of this department, on the one hand, with morphology, and on the other, with taxonomy, is clear. At the present time, phytopathology has received special development in North America, where almost half of all published botanical works fall to its share. 3. Genetics, which studies the mechanism of the origin of plant forms, should logically be brought closer to physiology, as it deals with known processes in plants; however, by its results, it is most closely connected with taxonomy. Genetics is a young branch of botany. Although its foundation was laid back in the middle of the 19th century by the works of Mendel, systematic development began only from the 20th century. At the present time, this branch is developing unusually quickly, so that now, by the number of published works, genetics yields little to other, older departments of botany and even sometimes surpasses them. In the subdivisions cited above, the entire world of plants is meant; however, it is possible (and this is in fact often the case) to limit the study to the limits of one particular group of plants, for example, fungi, mosses, etc. Thus, departments of special botany are obtained: mycology (study of fungi), bryology (study of mosses), etc. By their content, they more often adjoin taxonomy and, in part, morphology, but this is not always the case. For example, in bacteriology or the microbiology (see) close to it, the center of gravity is shifted precisely to the physiological features of the organisms being studied. Institutes, journals, societies, and teaching. Certain botanical questions, such as the study of the composition of vegetation of this or that locality, the clarification of certain phytogeographical data, etc., do not require any special environment for their development and are therefore fully accessible to amateurs, who, in general, still play a greater role in botany than in any other of the sciences of nature (perhaps the influence of those times when botany was a scientia amabilis is felt here). More scientific work requires, of course, a special environment and corresponding preparation. It is concentrated in botanical institutes, usually attached to academies and universities. Sometimes such institutes exist independently, pursuing, mostly, known applied goals (as, for example, in the USSR, the Institute of Applied Botany). The most common type of botanical institute is botanical gardens. In them, usually, not only are local and exotic plants cultivated, but there are also collections of dried plants (herbaria) and special laboratories for the production of scientific work. The largest botanical gardens of this kind are: the Royal Botanic Gardens, Kew near London, the Botanical Garden in Dahlem near Berlin, and in the USSR—the Main Botanical Garden in Leningrad. Scientific botanical societies exist in the majority of civilized countries. In addition, there exists an international botanical association, which published the main abstracting organ "Botanisches Centralblatt" (at the present time it is published by the German Botanical Society). Many national societies also publish scientific botanical journals, such as, for example: "Berichte der deutschen botanischen Gesellschaft", "Bulletin de la Société botanique de France", "American journal of botany", and in the USSR—"Journal of the Russian Botanical Society". Of other scientific botanical journals, the most important are: in Germany—"Flora" (the oldest journal, since 1818), "Botanische Zeitung" and the "Zeitschrift für Botanik" which replaced it in 1910, "Jahrbücher für wissenschaftliche Botanik"; in France—"Annales des sciences naturelles" (botanical series); in England—"Annals of botany"; in America—"Botanical gazette", and others. Scientific teaching of botany is concentrated in universities in the physics and mathematics (and analogous to them abroad) faculties and, in part, in some special schools, especially agricultural ones. In higher medical schools, there is also almost everywhere a special course in botany as an auxiliary and general educational discipline, while in Germany and especially in France, these courses are quite significant in volume. In the USSR, in medical faculties, until recently, there was also a special short course in botany. Recently, an experiment was made to combine botany with zoology into a general course of biology, in which it was intended, mainly, to combine general biological questions. This experiment has not yet been carried out everywhere and has not yet yielded clear results.