What Is Botany?

Botany is the branch of biology concerned with plants: their structure, physiology, genetics, classification, distribution, and interactions with the environment. Its scope has traditionally extended beyond the green plants to include algae, and historically fungi as well, although fungi are now placed in a separate kingdom and studied under mycology. The discipline covers organisms from single-celled green algae to the flowering plants that dominate terrestrial vegetation, and it addresses them at every level from chloroplast biochemistry to the composition of continental biomes.

The field is among the oldest organized sciences. Theophrastus, working in the fourth century BCE, wrote treatises on plant description and causation that remained the reference for nearly two millennia, and Linnaeus established binomial nomenclature in the eighteenth century, giving the discipline the naming system it still uses. Modern botany draws its methods from molecular biology, analytical chemistry, statistics, and increasingly from computation, while retaining the herbarium specimen and the field observation as primary records.

Systematics and Nomenclature

Plant systematics reconstructs evolutionary relationships and expresses them as a classification. The shift from morphology-based schemes to molecular phylogenetics reorganized the accepted arrangement of flowering plants substantially, and the successive classifications produced by the Angiosperm Phylogeny Group, documented on the Angiosperm Phylogeny Website maintained at the Missouri Botanical Garden, are the current reference for ordinal and familial limits. Names themselves are governed by the International Code of Nomenclature for algae, fungi, and plants, which fixes priority and typification. Because the same species has often been described more than once under different names, reconciled checklists matter: the USDA PLANTS Database provides standardized names and distribution data for the flora of the United States and its territories, and comparable national and global checklists serve the same function elsewhere.

Physiology, Anatomy, and Genetics

Plant physiology studies how plants capture and use energy and materials: photosynthetic carbon fixation through the Calvin cycle and its C4 and CAM variants, water transport through the xylem under tension, phloem loading of photosynthate, mineral nutrition, and hormonal control of growth by auxins, gibberellins, cytokinins, and abscisic acid. Anatomy examines the tissues that carry out this work, including meristems, vascular cambium, and stomatal guard cells. Genetics and genomics have become central since the sequencing of the Arabidopsis thaliana genome in 2000, and gene editing, transcriptomic profiling, and quantitative trait mapping now connect molecular variation to traits such as drought tolerance and disease resistance.

Ecology, Conservation, and Measurement

Plant ecology addresses population dynamics, community assembly, competition, succession, and the response of vegetation to climate and disturbance. Conservation botany assesses extinction risk and maintains living collections and seed banks against loss in the wild. Kew's State of the World's Plants and Fungi assessment compiles global species counts, extinction risk estimates, and the state of documentation, and reports that a large share of described flowering plants face extinction risk while many species remain undescribed. The instrumentation supporting this work has changed quickly: hyperspectral and multispectral imaging from satellites and unmanned aircraft, lidar for canopy structure, automated phenotyping platforms in growth chambers, environmental DNA sampling, and machine learning applied to digitized herbarium sheets and field photographs.

Applications

Botany supports work in a range of fields, including:

• Agriculture and crop breeding, including yield and stress tolerance improvement
• Forestry, rangeland management, and ecological restoration
• Pharmacognosy and natural product drug discovery
• Biofuel feedstock development and industrial plant biotechnology
• Environmental monitoring, remote sensing, and biodiversity informatics
• Horticulture, landscape design, and urban vegetation planning