Botany

Botany is a branch of biology that deals with the study of plants. In its broadest sense it would encompass all study concerning plant life, but it is usually limited to the study of the structure, physiology, development, genetics, ecology, and classification of plants, as well as economic botany and ethnobotany. These various specializations within botany provide the base for applied botany in other plant sci ences, such as horticulture, agriculture, forestry, plant breeding, and medical botany.

Structural botany encompasses plant anatomy and plant morphology. Plant anatomy concerns itself with the actual structure of plants in terms of cells and tissues, whereas plant morphology concerns itself mainly with form and life cycles. Each of these two subdisciplines has two approaches: comparative and developmental. The comparative approach is most commonly used to generate data for systematic purposes and for the description of form and structure to understand the functional aspects of structure for ecological studies. The latter approach is often termed ecological plant anatomy. In contrast, developmental approaches to structural botany are concerned with the development of cells, tissues, and form, and they tend to interface more closely with plant physiology and plant molecular biology. Plant physiology focuses on the chemistry and physics of water uptake and movement from the soil through the plant to the atmosphere, and on the translocation of assimilates throughout the plant. It also deals with ecophysiological adaptations, mineral nutrition, and the function of plant hormones in plant development. Plant molecular biology consists primarily of the identification and study of the genes that control development, organogenesis, physiology, and the production of plant secondary compounds. The latter studies interface with phy-tochemistry, which is involved in the identification and biosynthetic pathways of unique plant compounds that play an ecological role-and are an untapped source of potential pharmaceuticals.

Economic botany in the broadest sense is the study of plants and people. Historically, the area was mostly concerned with agricultural practices, both current and in the past, but more recently the focus has shifted toward the origin of cultivated crops—especially alternative crops found in tropical areas, in the search for new medicinals, and in ethnob-otany. Of particular concern is the study of local economies and plant use in order to develop sustainable agricultural and forestry practices with minimal environmental damage and long-term economic stability. Eth-nobotany interfaces substantially with anthropology, and ethnobotanists are concerned with the uses of plants by local people for medicines, food, clothing, building materials, and ceremonial purposes, in a concerted effort to preserve historical knowledge as well as to preserve and maintain local ecosystems and practices. The classifications used by indigenous people have often led to a new understanding of medical properties and to unsuspected evolutionary relationships.

Plant systematics is the study of the diversity of plant life in all environments; it involves the production of floras, monographs, and the classification of plants based upon our understanding of the evolutionary history of plant groups at all levels. Such data are gathered by plant systematists from all botanical subdisciplines (for example, anatomy phytochemistry, gene sequences, and so forth) in the reconstruction of the evolutionary history of the group(s) under study. Specialists within sys-tematics mainly concentrate on regions such as North America, China, and the like; or on habitats such as aquatic plants, desert plants, or tundra plants; or on groups of plants. The latter is more common, and some specialties in nonseed plants include phycology or algology (red, brown, and green algae), bryology (hornworts, liverworts, and mosses), and pteridology (club mosses, spike mosses, whisk ferns, horsetails, and ferns). Within seed plants, specialties include nonflowering seed plants or gym-nosperms (cycads, conifers, and gnetophytes) and flowering plants. The latter, by far the

A botanist nurtures seedlings in a greenhouse. (Library of Congress)

largest group of plants with minimally some 250,000 species, is further divided into many subgroups—for example, monocots, rosids, asterids, and so forth. The study of fungi (mycology) also is included within botany, although they are technically not plants, and these organisms are covered in botany textbooks and historically often included in floras. The understanding of the relationship of fungi to plants in terms of mycorhizal associations— that is, soil fungi with the roots of vascular plants—is fundamental in plant ecology and of value in plant systematics. Similarly, there is an association of plant pathogenic fungi, which often show coevolutionary relationships. The ultimate goal of plant systematics is to provide a classification system for all plants based upon their inferred evolutionary history.

Another important area in botany is paly-nology, which is the study of the pollen and spores of extant plants and in the fossil record as microfossils. Data from palynology are used in pollination biology, in systematics, to reconstruct prehistoric floras and climatic changes, and in medical studies of allergies. It is also an important source of data for the exploration for fossil fuels.

Paleobotany, the study of fossil plants, usually involves macrofossils (that is, roots, stems, leaves, cones, flowers, and so forth). The information obtained from paleobotanical studies is crucial for the development of a time line for the appearance of extant groups, the appearance of structural and reproductive innovations, and for understanding floristic changes. The distribution of fossil plants contributes significantly to understanding past climates and the geological processes leading to current and past distribution patterns so important in phyto-geography (the study of plant distribution).

In summary, the discipline of botany is essential to understanding the history of life on earth and the interactions of plants and people.

—Dennis Wm. Stevenson

See also: Angiosperms; Fungi; Gymnosperms; Lichens; Protoctists; Systematics

Bibliography

Bold, Harold C., Constantine J. Alexopoulos, and Theodore Delevoryas. 1987. Morphology of Plants and Fungi, 5th ed. New York: Harper and Row; Raven, Peter H., Ray F. Evert, and Susan E. Eichhorn. 1999. Biology of Plants, 6th ed. New York: W. H. Freeman; Scagel, Robert F., et al. 1982. Nonvascular Plants: An Evolutionary Survey. Belmont, CA: Wadsworth; Scagel, Robert F., et al. 1984. Plants: An Evolutionary Survey, 2d ed. Belmont, CA: Wadsworth; Simpson, Beryl B., and Molly Connor Ogorzaly. 2001. Economic Botany: Plants in Our World, 3d ed. Boston: McGraw-Hill.

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