III. Classical Studies

Gross observations and experiments on photosynthesis and the movement of water in plants can be made without knowledge of their structure, but explanations of these phenomena re­quire knowledge of morphology – the study and interpretation of plant form, development, and life histories – and of anatomy – the study of plant tissues and their origin and relations to one another. The cellular nature of plants was first pointed out by the English scientist Robert Hooke in the 17th century, when he observed that cork bark consists of cells. In 1838 the Ger­man botanist Matthias Schleiden proposed that all plant tissues consist of cells; this implied a basic sameness of living things and laid the foundation for the development of cytology, the study of the structure and function of cells as individual units rather than as aggregate tissue. The German pathologist Rudolf Virchow showed in 1858 that cells are derived from preexist­ing cells, and thus that a continuity exists between past and present living things.

Such observations were important not only in the development of plant physiology and anat­omy but also in the understanding of genetics, the science of heredity, and of evolution. In the 19th century the Austrian botanist Gregor Mendel worked out the basic principles of genetics, using varieties of garden peas and observing variations in their floral and vegetative features. His hybridization experiments required knowledge of the function of the various parts of the flower in reproduction, and this knowledge was derived from the experiments of the Dutch botanist Rudolph Jacob Camerarius, who established the nature of sexual reproduction in plants. Mendel's experiments went unnoticed until the early 1900s; in the meantime, Charles Darwin founded the theory of evolution (which in modern form depends on the principles of genetics) without knowledge of Mendel's work. Darwin observed variation and changes in or­ganisms through time, and Mendel worked out the laws governing the assortment and recom­bination of different traits. The source of differences and changes was not known, however, until the Dutch botanist Hugo Marie de Vries observed the spontaneous appearance of new traits in otherwise predictable crosses of evening primroses and suggested that these were the result of changes, or mutations, in the genes.

Knowledge of anatomy, genetics, and evolution has greatly advanced plant classification by providing a rational basis for this subdivision of botany. The 17th-century British naturalist John Ray divided plants into non-flowering and flowering types, and flowering plants into di­cots and monocots. The 18th-century Swedish botanist Carolus Linnaeus, however, provided the framework on which modern classifications are based and, just as important, a simplified system of nomenclature in which each plant is given two names: the first the name of the genus and the second the name of the species.

IV. Botany Today

Botany does not depend on the fossil record for information concerning evolution and classifi­cation as much as does zoology, because the record for plants is much less complete than that for animals. Nevertheless, paleobotany, the study of fossil plants, has contributed greatly to the overall understanding of the evolution of the major groups of plants and especially to under­standing of the interrelationships among the classes of seed plants. But much remains to be learned before fundamental questions such as the origin of the flowering plants can be answered.

Botanists – those engaged in the study of plants – occupy themselves with a broad range of activities. Many botanists are in academic positions that involve both teaching and research duties. The latter may involve laboratory work or field studies. Strictly speaking, botany is a pure science concerned with investigating the basic nature of plants. Many aspects of botany, how­ever, have direct importance to human welfare and advancement, and applied botany is an im­portant field. Such fields as forestry and horticulture are closely tied to basic botanical studies, whereas those such as pharmacology and agronomy are not as closely related but still depend on basic botanical knowledge.