Plant

Plant physiology is a subdiscipline of botany concerned with the functioning, or physiology, of plants.

Plant physiologists study fundamental processes of plants, such as photosynthesis, respiration, plant nutrition, plant hormone functions, tropisms, nastic movements, photoperiodism, photomorphogenesis, circadian rhythms, environmental stress physiology, seed germination, dormancy and stomata function and transpiration. Plant physiology interacts with the fields of plant morphology (structure of plants), plant ecology (interactions with the environment), phytochemistry (biochemistry of plants), cell biology, genetics, biophysics and molecular biology.

Biodiversity is the variability of life on Earth. It can be measured on various levels, for example, genetic variability, species diversity, ecosystem diversity and phylogenetic diversity. Diversity is not distributed evenly on Earth—it is greater in the tropics as a result of the warm climate and high primary productivity in the region near the equator. Tropical forest ecosystems cover less than one-fifth of Earth's terrestrial area and contain about 50% of the world's species. There are latitudinal gradients in species diversity for both marine and terrestrial taxa.

Since life began on Earth, six major mass extinctions and several minor events have led to large and sudden drops in biodiversity. The Phanerozoic aeon (the last 540 million years) marked a rapid growth in biodiversity via the Cambrian explosion. In this period, the majority of multicellular phyla first appeared. The next 400 million years included repeated, massive biodiversity losses. Those events have been classified as mass extinction events. In the Carboniferous, rainforest collapse may have led to a great loss of plant and animal life. The Permian–Triassic extinction event, 251 million years ago, was the worst; vertebrate recovery took 30 million years.

The Atlas Mountains are a mountain range in the Maghreb in North Africa. They separate the Sahara Desert from the Mediterranean Sea and the Atlantic Ocean; the mountain range stretches around 2,500 km (1,600 mi) through Morocco, Algeria and Tunisia. The mountains are associated with the Titan Atlas. The range's highest peak is Toubkal, in central Morocco, with an elevation of 4,167 metres (13,671 ft). The Atlas Mountains are primarily inhabited by Berber populations.

The terms for 'mountain' are Adrar and adras in some Berber languages, and these terms are believed to be cognates of the toponym Atlas. The mountains are home to a number of animals and plants which are mostly found within Africa but some of which can be found in Europe. Many of these species are endangered and a few are already extinct. The weather is generally cool but summers are sunny, and the average temperature there is 25 °C.

Human uses of plants include both practical uses, such as for food, clothing, and medicine, and symbolic uses, such as in art, mythology and literature. Materials derived from plants are collectively called plant products.

Edible plants have long been a source of nutrition for humans, and the reliable provision of food through agriculture and horticulture is the basis of civilization since the Neolithic Revolution. Medicinal herbs were and still remain to be the key ingredients of many traditional medicine practices, as well as being raw materials for some modern pharmaceuticals. The study of plant uses by native peoples is ethnobotany, while economic botany focuses on modern cultivated plants. Plants are also used as feedstock for many industrial products including timber, paper and textiles, as well as a wide range of chemicals.

Agronomy is the science and technology of producing and using plants by agriculture for food, fuel, fiber, chemicals, recreation, or land conservation. Agronomy has come to include research of plant genetics, plant physiology, meteorology, and soil science. It is the application of a combination of sciences such as biology, chemistry, economics, ecology, earth science, and genetics. Professionals of agronomy are termed agronomists.

A pheromone (from Ancient Greek φέρω (phérō) 'to bear' and hormone) is a chemical that is secreted or excreted by an organism, which triggers a social response in members of the same species. There are alarm pheromones, food trail pheromones, sex pheromones, and many others that affect behavior or physiology. Pheromones are used by many organisms, from basic unicellular prokaryotes to complex multicellular eukaryotes. Their use among insects has been particularly well documented. In addition, some vertebrates, plants and ciliates communicate by using pheromones. The ecological functions and evolution of pheromones are a major topic of research in the field of chemical ecology.

Pollination is the transfer of pollen from an anther of a plant to the stigma of a plant, later enabling fertilisation and the production of seeds. Pollinating agents can be animals such as insects, for example bees, beetles or butterflies; birds, and bats; water; wind; and even plants themselves. Pollinating animals travel from plant to plant carrying pollen on their bodies in a vital interaction that allows the transfer of genetic material critical to the reproductive system of most flowering plants. Self-pollination occurs within a closed flower. Pollination often occurs within a species. When pollination occurs between species, it can produce hybrid offspring in nature and in plant breeding work.

In angiosperms, after the pollen grain (gametophyte) has landed on the stigma, it germinates and develops a pollen tube which grows down the style until it reaches an ovary. Its two gametes travel down the tube to where the gametophyte(s) containing the female gametes are held within the carpel. After entering an ovule through the micropyle, one male nucleus fuses with the polar bodies to produce the endosperm tissues, while the other fuses with the egg cell to produce the embryo. Hence the term: "double fertilisation". This process would result in the production of a seed, made of both nutritious tissues and embryo.

Nectar is a viscous, sugar-rich liquid produced by plants in glands called nectaries, either within the flowers with which it attracts pollinating animals, or by extrafloral nectaries, which provide a nutrient source to animal mutualists, which in turn provide herbivore protection. Common nectar-consuming pollinators include mosquitoes, hoverflies, wasps, bees, butterflies and moths, hummingbirds, honeyeaters and bats. Nectar is an economically important substance as it is the sugar source for honey.

Nectar is also useful in agriculture and horticulture because the adult stages of some predatory insects feed on nectar. For example, a number of predacious or parasitoid wasps (e.g., the social wasp species Apoica flavissima) rely on nectar as a primary food source. In turn, these wasps then hunt agricultural pest insects as food for their young.

The wildlife of Brazil comprises all naturally occurring animals, plants, and fungi in Brazil, which is the most biodiverse country in the world. Home to 60% of the Amazon rainforest, which accounts for approximately one-tenth of all species in the world, Brazil has the greatest biodiversity of any country on the planet. It has the most known species of plants (60,000), freshwater fish (3,000), amphibians (1,188), snakes (430), insects (90,000) and mammals (775). Brazil is also the country with the most native species of eatable fruits (over 300).It also ranks third on the list of countries with the most bird species (1,971) and the third with the most reptile species (848). The number of fungal species is unknown (+3,300 species). Approximately two-thirds of all species worldwide are found in tropical areas, often coinciding with developing countries such as Brazil. Brazil is second only to Indonesia as the country with the most endemic species.

A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat non-vascular autotrophs such as mosses, algae and lichens, but do not include those feeding on decomposed plant matters (i.e. detritivores) or macrofungi (i.e. fungivores).

As a result of their plant-based diet, herbivorous animals typically have mouth structures (jaws or mouthparts) well adapted to mechanically break down plant materials, and their digestive systems have special enzymes (e.g. amylase and cellulase) to digest polysaccharides. Grazing herbivores such as horses and cattles have wide flat-crowned teeth that are better adapted for grinding grass, tree bark and other tougher lignin-containing materials, and many of them evolved rumination or cecotropic behaviors to better extract nutrients from plants. A large percentage of herbivores also have mutualistic gut flora made up of bacteria and protozoans that help to degrade the cellulose in plants, whose heavily cross-linking polymer structure makes it far more difficult to digest than the protein- and fat-rich animal tissues that carnivores eat.