Editing Botany (section)

== Scope and importance ==

[[File:Neuchâtel Herbarium - Athyrium filix-femina - NEU000003080.tif|left|thumb|upright|alt=A herbarium specimen of the lady fern, ''Athyrium filix-femina''|Botany involves the recording and description of plants, such as this herbarium specimen of the lady fern ''[[Athyrium filix-femina]]''.]]

The study of plants is vital because they underpin almost all animal life on Earth by generating a large proportion of the [[oxygen]] and food that provide humans and other organisms with [[cellular respiration|aerobic respiration]] with the chemical energy they need to exist. Plants, [[algae]] and [[cyanobacteria]] are the major groups of organisms that carry out [[photosynthesis]], a process that uses the energy of sunlight to convert water and [[carbon dioxide]]{{sfn|Campbell|Reece|Urry|Cain|2008|pp = 186–187}} into sugars that can be used both as a source of chemical energy and of organic molecules that are used in the structural components of cells.{{sfn|Campbell|Reece|Urry|Cain|2008|p = 1240}} As a by-product of photosynthesis, plants release [[oxygen]] into the atmosphere, a gas that is required by [[anaerobic organism|nearly]] all living things to carry out cellular respiration. In addition, they are influential in the global [[carbon cycle|carbon]] and [[water cycle|water]] cycles and plant roots bind and stabilise soils, preventing soil [[erosion]].{{sfn|Gust|1996}} Plants are crucial to the future of human society as they provide food, oxygen, [[biochemistry|biochemicals]], and products for people, as well as creating and preserving soil.{{sfn|Missouri Botanical Garden|2009}}

Historically, all living things were classified as either animals or plants{{sfn|Chapman et al.|2001|p = 56}} and botany covered the study of all organisms not considered animals.{{sfn|Braselton|2013}} Botanists examine both the internal functions and processes within plant [[organelle]]s, cells, tissues, whole plants, plant populations and plant communities. At each of these levels, a botanist may be concerned with the classification ([[Taxonomy (biology)|taxonomy]]), [[phylogeny]] and [[evolution]], structure ([[Plant anatomy|anatomy]] and [[Plant morphology|morphology]]), or function ([[Plant physiology|physiology]]) of plant life.{{sfn|Ben-Menahem|2009|p = 5368}}

The strictest definition of "plant" includes only the "land plants" or [[embryophytes]], which include [[seed plants]] (gymnosperms, including the [[Pinophyta|pines]], and [[flowering plant]]s) and the free-sporing [[cryptogams]] including [[fern]]s, [[Lycopodiopsida|clubmosses]], [[Marchantiophyta|liverworts]], [[hornwort]]s and [[moss]]es. Embryophytes are multicellular [[eukaryote]]s descended from an ancestor that obtained its energy from sunlight by [[photosynthesis]]. They have life cycles with [[alternation of generations|alternating]] haploid and [[diploid]] phases. The sexual [[haploid]] phase of embryophytes, known as the [[gametophyte]], nurtures the developing diploid embryo [[sporophyte]] within its tissues for at least part of its life,{{sfn|Campbell|Reece|Urry|Cain|2008|p = 602}} even in the seed plants, where the gametophyte itself is nurtured by its parent sporophyte.{{sfn|Campbell|Reece|Urry|Cain|2008|pp = 619–620}} Other groups of organisms that were previously studied by botanists include bacteria (now studied in [[bacteriology]]), fungi ([[mycology]]) – including [[lichen]]-forming fungi ([[lichenology]]), non-[[Chlorophyta|chlorophyte]] [[algae]] ([[phycology]]), and viruses ([[virology]]). However, attention is still given to these groups by botanists, and fungi (including lichens) and photosynthetic [[protist]]s are usually covered in introductory botany courses.{{sfn|Capon|2005|pp = 10–11}}{{sfn|Mauseth|2003|pp = 1–3}}

[[Paleobotany|Palaeobotanists]] study ancient plants in the fossil record to provide information about the [[evolutionary history of plants]]. [[Cyanobacteria]], the first oxygen-releasing photosynthetic organisms on Earth, are thought to have given rise to the ancestor of plants by entering into an [[endosymbiotic]] relationship with an early eukaryote, ultimately becoming the [[chloroplast]]s in plant cells. The new photosynthetic plants (along with their algal relatives) accelerated the rise in atmospheric [[oxygen]] started by the [[cyanobacteria]], [[great oxygenation event|changing]] the ancient oxygen-free, [[Redox|reducing]], atmosphere to one in which free oxygen has been abundant for more than 2 billion years.{{sfn|Cleveland Museum of Natural History|2012}}{{sfn|Campbell|Reece|Urry|Cain|2008|pp = 516–517}}

Among the important botanical questions of the 21st century are the role of plants as primary producers in the global cycling of life's basic ingredients: energy, carbon, oxygen, nitrogen and water, and ways that our plant stewardship can help address the global environmental issues of [[resource management]], [[Conservation (ethic)|conservation]], [[food security|human food security]], [[introduced species|biologically invasive organisms]], [[carbon sequestration]], [[climate change]], and [[sustainability]].{{sfn|Botanical Society of America|2013}}

=== Human nutrition ===
{{Further|Human nutrition}}
[[File:Brown rice.jpg|right|thumb|alt=grains of brown rice, a staple food|The food we eat comes directly or indirectly from plants such as rice.]]
Virtually all staple foods come either directly from [[primary production]] by plants, or indirectly from animals that eat them.{{sfn|Ben-Menahem|2009|pp = 5367–5368}} Plants and other photosynthetic organisms are at the base of most [[food chain]]s because they use the energy from the sun and nutrients from the soil and atmosphere, converting them into a form that can be used by animals. This is what ecologists call the first [[trophic level]].{{sfn|Butz|2007|pp = 534–553}} The modern forms of the major [[staple food]]s, such as [[hemp]], [[teff]], maize, rice, wheat and other cereal grasses, [[Pulse (legume)|pulses]], [[banana]]s and plantains,{{sfn|Stover|Simmonds|1987|pp=106–126}} as well as [[hemp]], [[flax]] and [[cotton]] grown for their fibres, are the outcome of prehistoric selection over thousands of years from among [[Neolithic founder crops|wild ancestral plants]] with the most desirable characteristics.{{sfn|Zohary|Hopf|2000|pp = 20–22}}

Botanists study how plants produce food and how to increase yields, for example through [[plant breeding]], making their work important to humanity's ability to feed the world and provide [[food security]] for future generations.{{sfn|Floros|Newsome|Fisher|2010}} Botanists also study weeds, which are a considerable problem in agriculture, and the biology and control of [[Plant pathology|plant pathogens]] in agriculture and natural [[ecosystems]].{{sfn|Schoening|2005}} [[Ethnobotany]] is the study of the relationships between plants and people. When applied to the investigation of historical plant–people relationships ethnobotany may be referred to as archaeobotany or [[paleoethnobotany|palaeoethnobotany]].{{sfn|Acharya|Anshu|2008|p = 440}} Some of the earliest plant-people relationships arose between the [[Indigenous peoples of the Americas|indigenous people]] of Canada in identifying edible plants from inedible plants. This relationship the indigenous people had with plants was recorded by ethnobotanists.{{sfn|Kuhnlein|Turner|1991}}