The Origins of Botany

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The Origins of Botany

Overview

Botany, the study of plants, developed as a science in ancient Greece, with Theophrastus (c. 371-287 b.c.) considered the father of botanical science. But a practical interest in plants extended far back before recorded times, because plants were not only a source of food but also of medicines. With the dawn of agriculture, interest in plant growth became more focused, as better methods for cultivating crops and protecting them from weather and pest damage were developed. Also, in many ancient civilizations, including those in China, Egypt, Babylonia, and Greece, sophisticated medical practices developed in which plant materials were important medicinals. What Theophrastus brought to such practical interests in plants was an inquiry that was more theoretical. After Theophrastus, botanical science progressed very little until the rediscovery of his writings in the fifteenth century, just as the Renaissance was beginning.

Background

Close observation is an important key to learning about nature for both practical and theoretical reasons, though most early interest in plant growth was clearly practical. It was related to finding and encouraging the growth of plants that were good sources of foods, medicines, building materials, and other products. Agriculture, which is the systematic growth of plants as opposed to just harvesting plant materials that happen to be available, is thought to have originated in western Asia at least 10,000 years ago.

By the time written documents came to be important in ancient times, several sophisticated civilizations had developed in different parts of the world, all with advanced agricultural practices based on close observation of geographic, climatic, and biological factors. The Egyptians had learned to harness the flood waters of the Nile River for irrigation, and with this came an interest in plants not only as food but for their use as medicine, as well as for decorative purposes in gardens. The Assyrians in Babylonia discovered sexual reproduction in date palms that allowed them to cultivate these trees, and from remote times the Chinese cultivated citrus fruits such as orange and lemons. Each of these civilizations also recorded information on the use of plant materials in the treatment of diseases. Plants were the primary sources of medicines in ancient times, and while each culture refined its own medical practices, there is also evidence that information from Egyptian and Babylonian medicine was used later by the Greeks.

The writings that are ascribed to Hippocrates (c. 460-377 b.c.), the greatest of the ancient Greek physicians, include descriptions of over 250 plants that were used either to promote health or cure disease. These documents also contain a great deal on proper diet as well as information on food plants. So it is clear that the Greeks studied plants for the very practical reasons of human health and nutrition. But in the sixth century b.c., an intellectual movement was developing in Greece, a movement leading to the development of Western philosophy, which asked basic questions less for their practical importance than for building a systematic exploration of the natural world.

The first Greek philosophers came from the island of Ionia. They investigated questions about such things as the origin of the world and its composition, and thus began a tradition that led to the development of scientific ways of thinking. The decline of the Ionian school was followed by such great Greek philosophers as Socrates (469-399 b.c.), Plato (c. 427-347 b.c.), and Aristotle (c. 384-322 b.c.). Of these, it was Aristotle who was most interested in the study of the living world, including plants. But as with many ancient writers, a great deal of what Aristotle wrote has been lost, including most of his botanical works. We can get some idea of his thoughts on plants from the writings of his student, Theophrastus. Theophrastus himself wrote more than 200 works, most of which have been lost. But two of his long works on botany have survived. Inquiry into Plants deals with the description and classification of about 550 plant species, and Causes of Plants discusses plant physiology and reproduction.

Impact

Because of the wealth of information and analysis found in these works, Theophrastus is called the father of botany. In Inquiry into Plants he describes not only those plants that are native to Greece, but also species that are found on the Atlantic coast, around the Mediterranean Sea, and even as far east as India. In both this work and Causes of Plants, he draws on the writings of earlier philosophers and scientists, including the Greeks Empedocles (c. 495-435 b.c.), Menestor, and Democritus (c. 460-370 b.c.), who had all written about plants. Theophrastus also includes reports from farmers, physicians, and others who had intimate knowledge of plants, so his writings contain a great deal of practical information and accurate observations.

In attempting to classify plants, Theophrastus argued that this task differed from the classification of animals because plants had less in common with each other than animals did. For example, he noted that while all animals he observed had in common a mouth and stomach, not all plants had leaves, stems, or even roots. For this reason, he thought that while the classification of animals could be based on generalizations, for plants it was specific features that were important. This meant that the essential thing was not reasoning to universals, but direct observation. Theophrastus used generalizations only when he had specific examples with which to support them. So even this early in the history of botany, there was a reliance on careful attention to detail.

It is not surprising that some of Theophrastus's observations are incomplete or inaccurate, considering that he didn't even have a hand lens with which to observe small plant structures. Still, he made a number of important and lasting contributions to botany. He was the first to distinguish between two basic categories of flowering plants, the monocots (those having a set of characteristics that include leaves with parallel veins) and dicots (those having leaves with branching veins). He also differentiated the flowering plants or angiosperms from the more primitive gymnosperms. In Causes of Plants he presented a great many observations on plant reproduction, including an accurate description of the germination of seeds, a description that was not improved upon until the seventeenth century.

Some historians of science consider Theophrastus to be the founder of the fields of plant geography and ecology because he didn't just describe the structural features of plants, but also wrote on the relationship between plant structure and habitat. He showed an awareness of plant communities, writing that certain groups of species were often found growing together in the same geographic areas or in the same types of environments. He also wrote of the adaptation of plants to particular environmental conditions, showing, for example, that some species were better adapted to dry conditions while others grew more vigorously in damp areas. In writing of plant pathology, he made a distinction between those diseases due to climate or soil conditions and those that were the result of pests.

The contributions of Theophrastus are particularly outstanding because they were not followed by work of comparable quality. Very little of scientific value was added to botanical knowledge until the Renaissance, which began in the fifteenth century, almost 2,000 years after the time of Theophrastus. Greek science, in general, declined after his time. Athens, which had been the seat of learning, faced political turmoil, and the center of Greek learning shifted to the city of Alexandria in Egypt. While there were a number of writers who produced works on botany, there was little new information in these works, and as the writings of Theophrastus continued to be copied, inaccuracies crept in. So botanical knowledge deteriorated rather than improved.

There were, however, a few figures who made lasting contributions to botany, though to a much lesser degree than Theophrastus. Two of the most noteworthy lived in the first century a.d. The Roman Pliny the Elder (a.d. 23-79) wrote Natural History, in which 16 of its 37 books were devoted to plants. Much of Pliny's information is based on the work of the Greek Crateuas (c. 120-60 b.c.) who had produced an herbal, a book on plants used in medicine, in the first century b.c. Pliny's botanical books contain a great deal of information on plants, though this material is not as well organized as that of Theophrastus because Pliny had little interest in classification. Pliny's writings are particularly important because they were highly valued during the Middle Ages, when they were copied many times, leading to the introduction of many errors. The works of Crateuas and Theophrastus, on the other hand, were lost, though Theophrastus's work was rediscovered in the fifteenth century.

The other first-century figure of note in botanical history is Pedanius Dioscorides (c. a.d. 40-90), a Greek born in Sicily. He wrote an herbal that was recopied many times in succeeding centuries, and became the main source of information on the medicinal uses of plants through the Middle Ages. At some point early in its history, Dioscorides's text was combined with illustrations from the herbal of Crateuas, whom Pliny described as the first to use botanical illustrations among the Greeks. It was the illustrated version of Dioscorides's work that was the subject of so much recopying, and this led to errors not only in the text but in the illustrations, which eventually became so simplified that it was impossible to identify the species from the illustrations.

It was in part because of the reliance of the scholars of the Middle Ages on such flawed documents that botanical science failed to progress very far beyond the contributions of Theophrastus. It was only in the late Middle Ages, with the work of scholars such as Albertus Magnus (1193-1280), that botanical science began to progress again. With the introduction of the printing press in the fifteenth century, accurate reproduction of texts and illustrations greatly spurred further development.

MAURA C. FLANNERY