Botany is the scientific study of plant life. As a branch of biology, it is also sometimes referred to as plant science(s) or plant biology. Botany covers a wide range of scientific disciplines that study the growth, reproduction, metabolism, development, diseases, and evolution of plants.
As with other life forms in biology, plant life can be studied at a variety of levels, from the molecular, genetic and biochemical level through to organelles, cells, tissues, organs and the biodiversity of whole plants. At the top end of this scale, plants can be studied in populations, communities and ecosystems (as in ecology). At each of these levels a botanist might be concerned with the classification (taxonomy), structure (anatomy), or function (physiology) of plant life.
Historically, botanists studied all organisms that were not generally regarded as animal. Some of these "plant-like" organisms include: fungi (studied in mycology); bacteria and viruses (studied in microbiology); and algae (studied in phycology). Most algae, fungi, and microbes are no longer considered to be in the plant kingdom. However, attention is still given to them by botanists; and bacteria, fungi, and algae are usually covered, somewhat superficially, in introductory botany courses.
So why study plants? Plants are an utterly fundamental part of life on earth. They generate the oxygen, food, fibres, fuel and medicine that allow higher life forms to exist. While doing all this, plants also absorb carbon dioxide, an important greenhouse gas, through photosynthesis. A good understanding of plants is crucial to the future of our society as it allows us to:
Virtually all of the food we eat comes from plants, either directly from staple foods and other fruit and vegetables, or indirectly through livestock which rely on plants for fodder. In other words, plants are at the base of nearly all food chains, or what ecologists call the first trophic level. Understanding how plants produce the food we eat is therefore important to be able to feed the world and provide food security for future generations, for example through plant breeding. Not all plants are beneficial to humans, weeds are a considerable problem in agriculture and botany provides some of the basic science in order to understand how to minimise their impact. Ethnobotany is the study this and other relationships between plants and people.
Plants are convenient organisms in which fundamental life processes (like cell division and protein synthesis for example) can be studied, without the ethical dilemmas of studying animals or humans. The genetic laws of inheritance were discovered in this way by Gregor Mendel who was studying the way pea shape is inherited. What Mendel learnt from studying plants has had far reaching benefits outside of botany.
More recently, Barbara McClintock discovered 'jumping genes' by studying maize. Although she was not a classical 'botanist' - her work demonstrates the ongoing relevance of studying plants to understand fundamental biological processes.
Many of our medicinal and recreational drugs, like cannabis, caffeine and nicotine come directly from the plant kingdom. Aspirin, which originally came from the bark of willow trees, is just one example. There may be many novel cures for diseases provided by plants, waiting to be discovered. Popular stimulants like coffee, chocolate, tobacco and tea also come from plants. Most alcoholic beverages, come from fermenting plants such as hops and grapes.
Plants also provide us with many natural materials: cotton, wood, paper, linen, vegetable oils, some types of rope and rubber are just a few examples that we often take for granted. The production of silk would not be possible without the cultivation of the mulberry plant. Sugarcane and other plants have recently been put to use as sources of biofuels which are important alternatives to fossil fuels.
These are just a handful of examples showing how plant life provides humanity with important medicine and materials.
Plants can also help us understand changes in on our environment in many ways.
So in many different ways, plants can act a bit like the 'miners canary', an early warning system alerting us to important changes in our environment. In addition to these practical and scientific reasons, plants are extremely valuable as recreation for millions of people who enjoy gardening, horticultural and culinary uses of plants everyday. Botanists also argue that botany is fascinating and rewarding topic of study in its own right.
A considerable amount of new knowledge today is being generated from studying model plants like Arabidopsis thaliana. This mustard weed was one of the first plants to have its genome sequenced. Other more commercially important plants like rice, wheat, maize and soybean are also having their genomes sequenced, although some of these are more challenging because they have more than two haploid (n) sets of chromosomes, a condition known as polyploidy. The "Green Yeast" Chlamydomonas reinhardtii (a single-celled, green alga) is another plant model organism that has been extensively studied and provided important insights into cell biology.
Among the earliest of botanical works, written around 300 BC, are two large treatises by Theophrastus: On the History of Plants (Historia Plantarum) and On the Causes of Plants. Together these books constitute the most important contribution to botanical science during antiquity and on into the Middle Ages. The Roman medical writer, Dioscorides, provides important evidence on Greek and Roman knowledge of officinal plants.
In 1665, using an early microscope, Robert Hooke discovered cells in cork; a short time later in living plant tissue. The German Leonhart Fuchs, the Swiss Conrad von Gesner, and the British authors Nicholas Culpeper and John Gerard, published herbals that gave information on the officinal uses of plants.