In botany, a tree is a perennial plant with an elongated stem, or trunk, supporting branches and leaves in most species. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are usable as lumber or plants above a specified height. Trees are not a taxonomic group but include a variety of plant species that have independently evolved a woody trunk and branches as a way to tower above other plants to compete for sunlight. Trees tend to be long-lived, some reaching several thousand years old. In wider definitions, the taller palms, tree ferns and bamboos are trees. Trees have been in existence for 370 million years, it is estimated. A tree has many secondary branches supported clear of the ground by the trunk; this trunk contains woody tissue for strength, vascular tissue to carry materials from one part of the tree to another. For most trees it is surrounded by a layer of bark. Below the ground, the roots spread out widely. Above ground, the branches divide into smaller shoots.
The shoots bear leaves, which capture light energy and convert it into sugars by photosynthesis, providing the food for the tree's growth and development. Trees reproduce using seeds. Flowers and fruit may be present, but some trees, such as conifers, instead have pollen cones and seed cones. Palms and bamboos produce seeds, but tree ferns produce spores instead. Trees play a significant role in moderating the climate, they remove carbon dioxide from the atmosphere and store large quantities of carbon in their tissues. Trees and forests provide a habitat for many species of plants. Tropical rainforests are among the most biodiverse habitats in the world. Trees provide shade and shelter, timber for construction, fuel for cooking and heating, fruit for food as well as having many other uses. In parts of the world, forests are shrinking as trees are cleared to increase the amount of land available for agriculture; because of their longevity and usefulness, trees have always been revered, with sacred groves in various cultures, they play a role in many of the world's mythologies.
Although "tree" is a term of common parlance, there is no universally recognised precise definition of what a tree is, either botanically or in common language. In its broadest sense, a tree is any plant with the general form of an elongated stem, or trunk, which supports the photosynthetic leaves or branches at some distance above the ground. Trees are typically defined by height, with smaller plants from 0.5 to 10 m being called shrubs, so the minimum height of a tree is only loosely defined. Large herbaceous plants such as papaya and bananas are trees in this broad sense. A applied narrower definition is that a tree has a woody trunk formed by secondary growth, meaning that the trunk thickens each year by growing outwards, in addition to the primary upwards growth from the growing tip. Under such a definition, herbaceous plants such as palms and papayas are not considered trees regardless of their height, growth form or stem girth. Certain monocots may be considered trees under a looser definition.
Aside from structural definitions, trees are defined by use. The tree growth habit is an evolutionary adaptation found in different groups of plants: by growing taller, trees are able to compete better for sunlight. Trees tend some reaching several thousand years old. Several trees are among the oldest organisms now living. Trees have modified structures such as thicker stems composed of specialised cells that add structural strength and durability, allowing them to grow taller than many other plants and to spread out their foliage, they differ from shrubs, which have a similar growth form, by growing larger and having a single main stem. The tree form has evolved separately in unrelated classes of plants in response to similar environmental challenges, making it a classic example of parallel evolution. With an estimated 60,000-100,000 species, the number of trees worldwide might total twenty-five per cent of all living plant species; the greatest number of these grow in tropical regions and many of these areas have not yet been surveyed by botanists, making tree diversity and ranges poorly known.
The majority of tree species are angiosperms. There are about 1000 species of gymnosperm trees, including conifers, cycads and gnetales. Most angiosperm trees are eudicots, the "true dicotyledons", so named because the seeds contain two cotyledons or seed leaves. There are some trees among the old lineages of flowering plants called basal angiosperms or paleodicots. Wood gives structural strength to the trunk of most types of tree; the vascular system of trees allows water and other chemicals to be di
Carl Linnaeus known after his ennoblement as Carl von Linné, was a Swedish botanist and zoologist who formalised binomial nomenclature, the modern system of naming organisms. He is known as the "father of modern taxonomy". Many of his writings were in Latin, his name is rendered in Latin as Carolus Linnæus. Linnaeus was born in the countryside of Småland in southern Sweden, he received most of his higher education at Uppsala University and began giving lectures in botany there in 1730. He lived abroad between 1735 and 1738, where he studied and published the first edition of his Systema Naturae in the Netherlands, he returned to Sweden where he became professor of medicine and botany at Uppsala. In the 1740s, he was sent on several journeys through Sweden to find and classify plants and animals. In the 1750s and 1760s, he continued to collect and classify animals and minerals, while publishing several volumes, he was one of the most acclaimed scientists in Europe at the time of his death. Philosopher Jean-Jacques Rousseau sent him the message: "Tell him I know no greater man on earth."
Johann Wolfgang von Goethe wrote: "With the exception of Shakespeare and Spinoza, I know no one among the no longer living who has influenced me more strongly." Swedish author August Strindberg wrote: "Linnaeus was in reality a poet who happened to become a naturalist." Linnaeus has been called Princeps botanicorum and "The Pliny of the North". He is considered as one of the founders of modern ecology. In botany and zoology, the abbreviation L. is used to indicate Linnaeus as the authority for a species' name. In older publications, the abbreviation "Linn." is found. Linnaeus's remains comprise the type specimen for the species Homo sapiens following the International Code of Zoological Nomenclature, since the sole specimen that he is known to have examined was himself. Linnaeus was born in the village of Råshult in Småland, Sweden, on 23 May 1707, he was the first child of Christina Brodersonia. His siblings were Anna Maria Linnæa, Sofia Juliana Linnæa, Samuel Linnæus, Emerentia Linnæa, his father taught him Latin as a small child.
One of a long line of peasants and priests, Nils was an amateur botanist, a Lutheran minister, the curate of the small village of Stenbrohult in Småland. Christina was the daughter of the rector of Samuel Brodersonius. A year after Linnaeus's birth, his grandfather Samuel Brodersonius died, his father Nils became the rector of Stenbrohult; the family moved into the rectory from the curate's house. In his early years, Linnaeus seemed to have a liking for plants, flowers in particular. Whenever he was upset, he was given a flower, which calmed him. Nils spent much time in his garden and showed flowers to Linnaeus and told him their names. Soon Linnaeus was given his own patch of earth. Carl's father was the first in his ancestry to adopt a permanent surname. Before that, ancestors had used the patronymic naming system of Scandinavian countries: his father was named Ingemarsson after his father Ingemar Bengtsson; when Nils was admitted to the University of Lund, he had to take on a family name. He adopted the Latinate name Linnæus after a giant linden tree, lind in Swedish, that grew on the family homestead.
This name was spelled with the æ ligature. When Carl was born, he was named Carl Linnæus, with his father's family name; the son always spelled it with the æ ligature, both in handwritten documents and in publications. Carl's patronymic would have been Nilsson, as in Carl Nilsson Linnæus. Linnaeus's father began teaching him basic Latin and geography at an early age; when Linnaeus was seven, Nils decided to hire a tutor for him. The parents picked a son of a local yeoman. Linnaeus did not like him, writing in his autobiography that Telander "was better calculated to extinguish a child's talents than develop them". Two years after his tutoring had begun, he was sent to the Lower Grammar School at Växjö in 1717. Linnaeus studied going to the countryside to look for plants, he reached the last year of the Lower School when he was fifteen, taught by the headmaster, Daniel Lannerus, interested in botany. Lannerus gave him the run of his garden, he introduced him to Johan Rothman, the state doctor of Småland and a teacher at Katedralskolan in Växjö.
A botanist, Rothman broadened Linnaeus's interest in botany and helped him develop an interest in medicine. By the age of 17, Linnaeus had become well acquainted with the existing botanical literature, he remarks in his journal that he "read day and night, knowing like the back of my hand, Arvidh Månsson's Rydaholm Book of Herbs, Tillandz's Flora Åboensis, Palmberg's Serta Florea Suecana, Bromelii Chloros Gothica and Rudbeckii Hortus Upsaliensis...."Linnaeus entered the Växjö Katedralskola in 1724, where he studied Greek, Hebrew and mathematics, a curriculum designed for boys preparing for the priesthood. In the last year at the gymnasium, Linnaeus's father visited to ask the professors how his son's studies were progressing. Rothman believed otherwise; the doctor offered to have Linnaeus live with his family in Växjö and to teach him physiology and botany. Nils accepted this offer. Rothman showed Linnaeus that botany was a serious sub
The subtropics are geographic and climate zones located between the tropics at latitude 23.5° and temperate zones north and south of the Equator. Subtropical climates are characterized by warm to hot summers and cool to mild winters with infrequent frost. Most subtropical climates fall into two basic types: humid subtropical, where rainfall is concentrated in the warmest months, dry summer climate or, where seasonal rainfall is concentrated in the cooler months. Subtropical climates can occur at high elevations within the tropics, such as in the southern end of the Mexican Plateau and in Vietnam and Taiwan. Six climate classifications use the term to help define the various temperature and precipitation regimes for the planet Earth. A great portion of the world's deserts are located within the subtropics, due to the development of the subtropical ridge. Within savanna regimes in the subtropics, a wet season is seen annually during the summer, when most of the yearly rainfall falls. Within Mediterranean climate regimes, the wet season occurs during the winter.
Areas bordering warm oceans are prone to locally heavy rainfall from tropical cyclones, which can contribute a significant percentage of the annual rainfall. Plants such as palms, mango, pistachio and avocado are grown within the subtropics; the tropics have been defined as lying between the Tropic of Cancer and Tropic of Capricorn, located at latitudes 23.45° north and south, respectively. According to the American Meteorological Society, the poleward fringe of the subtropics is located at latitudes 35° north and south, respectively. Several methods have been used to define the subtropical climate. In the Trewartha climate classification, a subtropical region should have at least eight months with a mean temperature greater than 10 °C and at least one month with a mean temperature under 18 °C. German climatologists Carl Troll and Karlheinz Paffen defined Warm temperate zones as plain and hilly lands having an average temperature of the coldest month between 2 °C and 13 °C in the Northern Hemisphere and between 6 °C and 13 °C in the Southern Hemisphere, excluding oceanic and continental climates.
According to the Troll-Paffen climate classification, there exists one large subtropical zone named the warm-temperate subtropical zone, subdivided into seven smaller areas. According to the E. Neef climate classification, the subtropical zone is divided into two parts: Rainy winters of the west sides and Eastern subtropical climate. According to the Wilhelm Lauer & Peter Frankenberg climate classification, the subtropical zone is divided into three parts: high-continental and maritime. According to the Siegmund/Frankenberg climate classification, subtropical is one of six climate zones in the world. Heating of the earth near the equator leads to large amounts of upward motion and convection along the monsoon trough or intertropical convergence zone; the upper-level divergence over the near-equatorial trough leads to air rising and moving away from the equator aloft. As the air moves towards the mid-latitudes, it cools and sinks, which leads to subsidence near the 30th parallel of both hemispheres.
This circulation leads to the formation of the subtropical ridge. Many of the world's deserts are caused by these climatological high-pressure areas, located within the subtropics; this regime is known as an arid subtropical climate, located in areas adjacent to powerful cold ocean currents. Examples of this climate are the coastal areas of southern Africa, the south of the Canary Islands and the coasts of Peru and Chile; the humid subtropical climate is located on the western side of the subtropical high. Here, unstable tropical airmasses in summer bring convective overturning and frequent tropical downpours, summer is the season of peak annual rainfall. In the winter the monsoon retreats, the drier trade winds bring more stable airmass and dry weather, frequent sunny skies. Areas that have this type of subtropical climate include Australia, Southeast Asia, parts of South America, the deep south of the United States. In areas bounded by warm ocean like the southeastern United States and East Asia, tropical cyclones can contribute to local rainfall within the subtropics.
Japan receives over half of its rainfall from typhoons. The Mediterranean climate is a subtropical climate with a wet season in winter and a dry season in the summer. Regions with this type of climate include the rim lands of the Mediterranean Sea, southwestern Australia around the Perth area, parts of the west coast of South American around Santiago, the coastal areas of western Mexico, coastal California in the United States; these climates do not see hard frosts or snow, which allows plants such as palms and citrus to flourish. As one moves toward the tropical side the slight winter cool season disappears, while at the poleward threshold of the subtropics the winters become cooler; some crops which have been traditionally farmed in tropical climates, such as mango and avocado, are cultivated in the subtropics. Pest control of the crops is less difficult than within the tropics, due to the cooler winters. Tree ferns are grown within subtropical areas within the subtropics and within topography within the tropics.
Dracaena and yucca can grow within the subtropics. Tre
Augustin Pyramus de Candolle
Augustin Pyramus de Candolle spelled Augustin Pyrame de Candolle was a Swiss botanist. René Louiche Desfontaines launched de Candolle's botanical career by recommending him at an herbarium. Within a couple of years de Candolle had established a new genus, he went on to document hundreds of plant families and create a new natural plant classification system. Although de Candolle's main focus was botany, he contributed to related fields such as phytogeography, paleontology, medical botany, economic botany. Candolle originated the idea of "Nature's war", which influenced Charles Darwin and the principle of natural selection. De Candolle recognized that multiple species may develop similar characteristics that did not appear in a common evolutionary ancestor. During his work with plants, de Candolle noticed that plant leaf movements follow a near-24-hour cycle in constant light, suggesting that an internal biological clock exists. Though many scientists doubted de Candolle's findings, experiments over a century demonstrated that ″the internal biological clock″ indeed exists.
Candolle's descendants continued his work on plant classification. Alphonse de Candolle and Casimir Pyrame de Candolle contributed to the Prodromus Systematis Naturalis Regni Vegetabilis, a catalog of plants begun by Augustin Pyramus de Candolle. Augustin Pyramus de Candolle was born on 4 February 1778 in Geneva, Switzerland, to Augustin de Candolle, a former official, his wife, Louise Eléonore Brière, his family descended from one of the ancient families of Provence in France, but relocated to Geneva at the end of the 16th century to escape religious persecution. At age seven de Candolle contracted of a severe case of hydrocephalus, which affected his childhood, he is said to have had great aptitude for learning, distinguishing himself in school with his rapid acquisition of knowledge in classical and general literature and his ability to write fine poetry. In 1794, he began his scientific studies at the Collège Calvin, where he studied under Jean Pierre Étienne Vaucher, who inspired de Candolle to make botanical science the chief pursuit of his life.
He spent four years at the Geneva Academy, studying science and law according to his father's wishes. In 1798, he moved to Paris, his botanical career formally began with the help of René Louiche Desfontaines, who recommended de Candolle for work in the herbarium of Charles Louis L'Héritier de Brutelle during the summer of 1798. The position elevated de Candolle's reputation and led to valuable instruction from Desfontaines himself. De Candolle established his first genus, Senebiera, in 1799.de Candolle's first books, Plantarum historia succulentarum and Astragalogia, brought him to the notice of Georges Cuvier and Jean-Baptiste Lamarck. de Candolle, with Cuvier's approval, acted as deputy at the Collège de France in 1802. Lamarck entrusted him with the publication of the third edition of the Flore française, in the introduction entitled Principes élémentaires de botanique, de Candolle proposed a natural method of plant classification as opposed to the artificial Linnaean method; the premise of de Candolle's method is.
In 1804, de Candolle published his Essai sur les propriétés médicales des plantes and was granted a doctor of medicine degree by the medical faculty of Paris. Two years he published Synopsis plantarum in flora Gallica descriptarum. de Candolle spent the next six summers making a botanical and agricultural survey of France at the request of the French government, published in 1813. In 1807 he was appointed professor of botany in the medical faculty of the University of Montpellier, where he would become the first chair of botany in 1810, his teaching at the University of Montpellier consisted of field classes attended by 200–300 students, starting at 5:00 am and finishing at 7:00 pm. While in Montpellier, de Candolle published his Théorie élémentaire de la botanique, which introduced a new classification system and the word taxonomy. Candolle moved back to Geneva in 1816 and in the following year was invited by the government of the Canton of Geneva to fill the newly created chair of natural history.
De Candolle spent the rest of his life in an attempt to elaborate and complete his natural system of botanical classification. De Candolle published initial work in his Regni vegetabillis systema naturale, but after two volumes he realized he could not complete the project on such a large scale, he began his less extensive Prodromus Systematis Naturalis Regni Vegetabilis in 1824. However, he was able to finish two-thirds of the whole. So, he was able to characterize over one hundred families of plants, helping to lay the empirical basis of general botany. Although de Candolle's main focus was botany, throughout his career he dabbled in fields related to botany, such as phytogeography, paleontology, medical botany, economic botany. In 1827 he was elected an associated member of the Royal Institute of the Netherlands. Augustin de Candolle was the first of four generations of botanists in the de Candolle dynasty, his son, Alphonse de Candolle, whom he fathered with his wife, Mademoiselle Torras succeeded to his father's chair in botany and continued the Prodromus.
Casimir Pyrame de Candolle, Augustin de Candolle's grandson contributed to the Prodromus through his detailed, extensive research and characterization of the Piperaceae family of plants. Augustin de Candolle's great-grandson, Richard Émile Augustin de Candolle
Tannins are a class of astringent, polyphenolic biomolecules that bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids. The term tannin refers to the use of oak and other bark in tanning animal hides into leather. By extension, the term tannin is applied to any large polyphenolic compound containing sufficient hydroxyls and other suitable groups to form strong complexes with various macromolecules; the tannin compounds are distributed in many species of plants, where they play a role in protection from predation and might help in regulating plant growth. The astringency from the tannins is what causes the dry and puckery feeling in the mouth following the consumption of unripened fruit, red wine or tea; the destruction or modification of tannins with time plays an important role when determining harvesting times. Tannins have molecular weights ranging from 500 to over 3,000 and up to 20,000. There are three major classes of tannins: Shown below are the base unit or monomer of the tannin.
In the flavone-derived tannins, the base shown must be hydroxylated and polymerized in order to give the high molecular weight polyphenol motif that characterizes tannins. Tannin molecules require at least 12 hydroxyl groups and at least five phenyl groups to function as protein binders. Oligostilbenoids constitute a class of tannins. Pseudo tannins are low molecular weight compounds associated with other compounds, they do not change color during the Goldbeater's skin test, unlike hydrolysable and condensed tannins, cannot be used as tanning compounds. Some examples of pseudo tannins and their sources are: Ellagic acid, gallic acid, pyrogallic acid were first discovered by chemist Henri Braconnot in 1831. Julius Löwe was the first person to synthesize ellagic acid by heating gallic acid with arsenic acid or silver oxide. Maximilian Nierenstein studied natural tannins found in different plant species. Working with Arthur George Perkin, he prepared ellagic acid from algarobilla and certain other fruits in 1905.
He suggested its formation from galloyl-glycine by Penicillium in 1915. Tannase is an enzyme, he proved the presence of catechin in cocoa beans in 1931. He showed in 1945 that luteic acid, a molecule present in the myrobalanitannin, a tannin found in the fruit of Terminalia chebula, is an intermediary compound in the synthesis of ellagic acid. At these times, molecule formulas were determined through combustion analysis; the discovery in 1943 by Martin and Synge of paper chromatography provided for the first time the means of surveying the phenolic constituents of plants and for their separation and identification. There was an explosion of activity in this field after 1945, including prominent work by Edgar Charles Bate-Smith and Tony Swain at Cambridge University. In 1966, Edwin Haslam proposed a first comprehensive definition of plant polyphenols based on the earlier proposals of Bate-Smith and Theodore White, which includes specific structural characteristics common to all phenolics having a tanning property.
It is referred to as the White–Bate-Smith–Swain–Haslam definition. Tannins are distributed in species throughout the plant kingdom, they are found in both gymnosperms as well as angiosperms. Mole studied the distribution of tannin in 180 families of dicotyledons and 44 families of monocotyledons. Most families of dicot contain tannin-free species; the best known families of which all species tested contain tannin are: Aceraceae, Anacardiaceae, Burseraceae, Dipterocarpaceae, Grossulariaceae, Myricaceae for dicot and Najadaceae and Typhaceae in Monocot. To the family of the oak, Fagaceae, 73% of the species tested contain tannin. For those of acacias, only 39% of the species tested contain tannin, among Solanaceae rate drops to 6% and 4% for the Asteraceae; some families like the Boraginaceae, Papaveraceae contain no tannin-rich species. The most abundant polyphenols are the condensed tannins, found in all families of plants, comprising up to 50% of the dry weight of leaves. Tannins of tropical woods tend to be of a cathetic nature rather than of the gallic type present in temperate woods.
There may be a loss in the bio-availability of still other tannins in plants due to birds and other pathogens. Tannins are found in leaf, seed and stem tissues. An example of the location of the tannins in stem tissue is that they are found in the growth areas of trees, such as the secondary phloem and xylem and the layer between the cortex and epidermis. Tannins may help regulate the growth of these tissues. In all vascular plants studied so far, tannins are manufactured by a chloroplast-derived organelle, the tannosome. Tannins are physically located in the vacuoles or surface wax of plants; these storage sites keep tannins active against plant predators, but keep some tannins from affecting plant metabolism while the plant tissue is alive. Tannins are classified as ergastic substances, i.e. non-protoplasm materials found in cells. Tannins, by definition, precipitate proteins. In this condition, they must be stored in organelles able to withstand the protein precipitation process. Idioblasts are isolated plant cells which differ from neighbo
Klondike Mountain Formation
The Klondike Mountain Formation is an early Eocene geological formation located in the northeast central area of Washington State. The formation, named for the type location designated in 1962, Klondike Mountain north of Republic, Washington, is composed of volcanic rocks in the upper unit and volcanics plus lacustrine sedimentation in which a lagerstätte with exceptionally well-preserved plant and insect fossils has been found, along with fossil epithermal hot springs; the formation is the youngest in a group of formations. The formation unconformably overlies rocks of the Eocene Sanpoil Volcanics and much older Triassic and Permian formations; the formation is bounded on its edges by a series of high-angle strike slip faults, which have contained the Klondike Mountain Formation in a series of graben structures, such as the Republic Graben. The formation is located in northern Ferry County, with the majority of the sedimentation in the Republic and Curlew Basins on the east and in the Toroda Creek area to the north west.
The town of Republic, Washington is situated at the southern end of the formation, with outcrops within the city itself. The Curlew basin is situated north of Republic, with the northern edge along the Kettle River and the community of Curlew, Washington near the northeastern edge; the formation is the southernmost of a string of preserved Eocene highland lakebeds in Washington state and British Columbia. The lake system, within the Okanagan highlands, extends from the Klondike Mountain Formation north 1,000 kilometres in to southern central British Columbia. Early dating of the formation was based on identification and correlation of the fossils found in the Tom Thumb Tuff, with Joseph Umpleby in 1910 reporting a putative age of early Miocene; this date was based in examination of fossils by C. R. Eastman, who thought them to be similar to those found in the Florissant Formation of Colorado, which at the time was considered Miocene; this age was retained in the 1928 work of Edward W. Berry, who included the Klondike Mountain Formation fossil lakebeds as part of the Latah Formation.
The age of the Formation has been revised in the following hundred years, with Roland W. Brown identifying the deposits as being older than the Latah Formation in 1936. In a written communication circa 1958, Brown again revised the age still older, stating the fossils found in the area of Mount Elizabeth indicated an Oligocene age; this age was used by R. L. Parker and J. A. Calkins in their 1964 work on the Curlew Quadrangle of Ferry County. Since the fossil-bearing strata of the Formation have been radiometrically dated, to give a current estimate of the Ypresian, the mid stage of the early Eocene,49.4 ±.5 million years ago. Parker and Calkins in 1964 noted the association of the Klondike Mountain Formation with the gold and silver deposits of the Republic District and suggested it as a potential host to more ore deposits in the Curlew Quadrangle; the epithermal gold deposits occurring in the Sanpoil volcanics terminate directly below the unconformity where the volcanics contact the base of the Klondike Mountain Formation or sometimes penetrate into the Formation's lowest unit.
Hydrothermal sinter deposits are known from the lowest portions of the Formation and are thought to represent hydrothermal eruption areas. In general the lower portions of the Formation have a large amount of hydrothermal alteration, areas around vents are rich in pyrite and silica. Two products of natural hydrothermic sintering; the areas above that show a transition to mudstones and sandstones grading from fine-grained material into coarser materials moving up the strata column. The finely-bedded stones show the greatest numbers of fossils and the finest preservation of details; the lake bed sediments preserve a diverse array of plants and fishes, notably the biota called the Republic flora. The Okanagan lake system, which includes the Klondike Mountain Formation, has been classified as one of the great Canadian lagerstätten; the paleoenvironment preserved in the lake deposits is that of a mesic forest, similar in rainfall to that found today along the modern Washington State and British Columbia coast.
The climate of the region offered a moderate amount of summer heat, with chilly winters not cold enough to sustain snow cover. Over a dozen different Rosaceae genera, both extant and extinct, have been identified in the formation; these fossils are some of the oldest reliable macrofossils for the family. The neuropteran insects identified as of 2014 include species from the families Berothidae, Hemerobiidae, Nymphidae and Psychopsidae. A number of mecopteran species belonging to the families Cimbrophlebiidae, Dinopanorpidae and Panorpidae are known
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants. The biological function of a flower is to effect reproduction by providing a mechanism for the union of sperm with eggs. Flowers may allow selfing; some flowers produce diaspores without fertilization. Flowers are the site where gametophytes develop. Many flowers have evolved to be attractive to animals, so as to cause them to be vectors for the transfer of pollen. After fertilization, the ovary of the flower develops into fruit containing seeds. In addition to facilitating the reproduction of flowering plants, flowers have long been admired and used by humans to bring beauty to their environment, as objects of romance, religion, medicine and as a source of food; the essential parts of a flower can be considered in two parts: the vegetative part, consisting of petals and associated structures in the perianth, the reproductive or sexual parts. A stereotypical flower consists of four kinds of structures attached to the tip of a short stalk.
Each of these kinds of parts is arranged in a whorl on the receptacle. The four main whorls are as follows: Collectively the calyx and corolla form the perianth. Calyx: the outermost whorl consisting of units called sepals. Corolla: the next whorl toward the apex, composed of units called petals, which are thin and colored to attract animals that help the process of pollination. Androecium: the next whorl, consisting of units called stamens. Stamens consist of two parts: a stalk called a filament, topped by an anther where pollen is produced by meiosis and dispersed. Gynoecium: the innermost whorl of a flower, consisting of one or more units called carpels; the carpel or multiple fused carpels form a hollow structure called an ovary, which produces ovules internally. Ovules are megasporangia and they in turn produce megaspores by meiosis which develop into female gametophytes; these give rise to egg cells. The gynoecium of a flower is described using an alternative terminology wherein the structure one sees in the innermost whorl is called a pistil.
A pistil may consist of a number of carpels fused together. The sticky tip of the pistil, the stigma, is the receptor of pollen; the supportive stalk, the style, becomes the pathway for pollen tubes to grow from pollen grains adhering to the stigma. The relationship to the gynoecium on the receptacle is described as hypogynous, perigynous, or epigynous. Although the arrangement described above is considered "typical", plant species show a wide variation in floral structure; these modifications have significance in the evolution of flowering plants and are used extensively by botanists to establish relationships among plant species. The four main parts of a flower are defined by their positions on the receptacle and not by their function. Many flowers lack some parts or parts may be modified into other functions and/or look like what is another part. In some families, like Ranunculaceae, the petals are reduced and in many species the sepals are colorful and petal-like. Other flowers have modified stamens.
Flowers show great variation and plant scientists describe this variation in a systematic way to identify and distinguish species. Specific terminology is used to describe their parts. Many flower parts are fused together; when petals are fused into a tube or ring that falls away as a single unit, they are sympetalous. Connate petals may have distinctive regions: the cylindrical base is the tube, the expanding region is the throat and the flaring outer region is the limb. A sympetalous flower, with bilateral symmetry with an upper and lower lip, is bilabiate. Flowers with connate petals or sepals may have various shaped corolla or calyx, including campanulate, tubular, salverform or rotate. Referring to "fusion," as it is done, appears questionable because at least some of the processes involved may be non-fusion processes. For example, the addition of intercalary growth at or below the base of the primordia of floral appendages such as sepals, petals and carpels may lead to a common base, not the result of fusion.
Many flowers have a symmetry. When the perianth is bisected through the central axis from any point and symmetrical halves are produced, the flower is said to be actinomorphic or regular, e.g. rose or trillium. This is an example of radial symmetry; when flowers are bisected and produce only one line that produces symmetrical halves, the flower is said to be irregular or zygomorphic, e.g. snapdragon or most orchids. Flowers may be directly attached to the plant at their base; the stem or stalk subtending a flower is called a peduncle. If a peduncle supports more than o