Botany

The science of plants. Botany is divided into various sub-divisions: systemic botany, plant morphology, and plany phsiology are the most notable.

Systematic Botany (aka plant taxonomy)

Systematic botany deals with names and classifications of plants. Its object is to identify by name and description all the kinds of plants which can be distinguished, and to arrange them, according to their natural relationships, into those groups which we call species, genera, families and orders. Since these relationships can be determined only after a knowledge of evolutionary history, the science of Plant Phylogeny, which endeavors to trace the genealogy of the plant kingdom, is an important adjunct to systematic botany.

Plant Morphology

Plant morphology deals with the form and structure of plants. Its object is to descibe the construction and organization of the plant body and to trace underlying similarities in form between various plant groups. Under morphology are included Anatomy, dealing with internal structures in general; Histology, with the more minute internal structures; Cytology, with the structure of the cell; Embryology, with the development of the individual, and Experimental Morphology, with the causes which determine form and structure..

Plant Physiology

Plant physiology deals with the functions of plants. Its objects are to describe and explain the various activities by which the life of the plant is maintained and transmitted to its offspring. Physiology obviously underlies the other sub-divisions of botany since it touches the very process of living. A branch of physiology particularly active today is Genetics, which deals with the problems of inheritance.


Aside from these three major sub-sciences there are other fields of botany which deserve mention. Plant Ecology is concerned with the relations between plants and the various factors of their environment such as soil, climatic conditions and living organisms; and, in particular, with the modifications of structure and function which enable them to react successfully to changes in their surroundings. Ecology necessarily involves both morphology and physiology, as well as certain of the physical sciences. Plant Geography is concerned with the geographical distribution of plants, and is intimately related both to systematic botany and to ecology, as well as to geology and geography. Palaeobotany is concerned with the structure and relationships of fossil plants, and thus touches systematic botany, morphology, and geology.

In addition to all these aspects of botany, most of which are theoretical rather than practical in their bearing, we should not fail to mention the great group of sciences concerned with the utilization and culture of plants. Economic Botany, in its narrower sense, is a study of those plants which are valuable to man and of the uses to which they are put. The various sciences commonly grouped under Agriculture (Soil Science, Agronomy, Horticulture, Plant Pathology, and many others) together with Forestry, Pharmacology and their subsidiaries, are eminently practical, and their close relationship to botany is sometimes overlooked. They are nevertheless integral parts of our science, and for their successful pursuit demand a sound knowledge of botanical principles. Everyone who is concerned with plants from a scientific point of view, whatever his purpose or profession, is rightfully to be called a botanist.


History

The Classical Period

Botany as we know it today is the result of a long term of observation and inquiry. As do so many other sciences, it looks back to the fertile speculations of the Greeks for the first definite expression of its problems and principles. The “nature” of plants was studied by Aristotle (384-322 B.C.) who saw clearly certain of the broader problems of plant and animal life, and whose sagacious comments thereon are still worthy of our attention. It is his disciple Theophrastus of Eresus (371-287 BC), however, whom botanists have generally regarded as the father of their science. This keen naturalist accumulated a great mass of information with regard to plants and discussed their various characteristics. Rome also had her share in the development of plant science, notably through the contributions of Pliny the Elder (23-79 AD), whose “Natural History” a compendium of facts and fancies about living things, was long a storehouse of botanical information. Dioscorides, living at about the time of Nero, studied plants for their medicinal properties and holds an important place historically in both botany and medicine.

The Herbalists

After this, its classical period, botany went into that profound eclipse suffered by all sciences during the Middle Ages. The teachings of the ancient masters were jealously preserved and were commented upon and dissected, but the thought of extending knowledge by direct observation and experiment was held to be almost sacrilegious. About the beginning of the sixteenth century, however, a group of open-minded men living in the Rhine valley and its adjacent regions undertook to explore the plant kingdom afresh for themselves. They were interested in plants chiefly for the curative virtues to be found therein, and, paying scant attention to the doctrines and dogmas of the ancients, they went about describing and drawing with fidelity the various kinds of plants which flourished their native countries. From the numerous herb-books or “Herbals” in which the resulting discoveries were published, these pioneers have been known as the “Herbalists”. They endeavored to distinguish clearly the different species from one another, and proposed certain crude methods of classifying the plant kingdom. So unprejudiced and free from conventional dogmatism of the age was their whole attitude that the Herbalists are generally regarded as the fathers of modern botany.

The Modern Period

The first extensive and thorough classification of plants was that proposed in 1583 by the Italian botanist Cesalpino (1519-1603). Combining an acquaintance with the ancients and an intimate first-hand knowledge of plants, he laid down certain principles which were the basis of systematic botany for many years. Modern taxonomy, however, dates from the publication of the “Species Plantarum” by the great Swedish naturalist Linnaeus (1707-1778), in 1753. In this monumental book all the plant species known at that time were named, carefully described, and arranged according to a definite system.

Although the early work in botany was thus concerned chiefly with taxonomy, the study of plant structures was not neglected Grew (1628-1711) in England, and Malpighi (1628-1694) in Italy, were keenly interested in the internal construction of the plant body, and their works on “phytotomy” laid the foundation for our modern knowledge of plant morphology. The continued improvement in the compound microscope made possible more complete and accurate knowledge of the way plants are constructed, and led to the formation by Schleiden, in 1838, of the Cell Theory, which states that the cell is the unit of structure in plants and that protoplasm is its essential constituent. From this beginning, modern anatomy and cytology have added a great body of facts to our knowledge of the structure, growth, and reproduction of the plant body.

The ancients and early modern botanists for the most part had fanciful and inaccurate ideas as to the way in which the plant had carried on its various functions, an ignorance largely due to the undeveloped state of the sciences of physics and chemistry at the time. It was not until the latter part of the eighteenth century that modern plant physiology became definitely established. Oxygen was discovered by Priestly in 1774, and five years later a Dutch physician, Ingenhousz, observed that green plants in the light take in carbon dioxide and give off oxygen, and that all plants give off a certain amount of carbon dioxide. These gas exchanges were accurately measured by de Saussure in the early years of the nineteenth century, and some of the important facts of plant physiology thus became established. Since that time the development of modern chemistry and physics has made possible a steady advance in our knowledge of the physiological processes of living things.

The publication of the “Origin of Species” by Charles Darwin in 1859 resulted in a general acceptance among scientists of the theory of evolution. A recognition of the fact that the plants of today have been slowly developed from simpler ancestors has had a profound effect upon botanical science and has stimulated a great interest in reconstructing the “family tree” of the plant kingdom and establishing a really “natural” system of classification, based on actual relationship, to replace the artificial systems of Linnaeus and his predecessors. It has led also to a more intensive study of the laws of variation and inheritance, and the causes and method of evolution. This has been encouraged still further by the discovery of Mendels Law of Inheritance, propounded in 1866, disregarded for many years, and finally brought to the attention of biologists again in 1900.

The present state of the science of botany, then, is the result of a long period of slow development, in which truth has been gradually separated from error and our present vast store of facts amassed. With each advance, new questions have arisen and new fields of investigation have opened, until the science has broadened from a mere discussion of the names and properties of medicinal herbs to an attack upon the fundamental problems of life itself.


Further Readings


All information is sourced from Botany: Principles and Problems by Edmund W. Sinnot, unless otherwise specified.