Species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. While these definitions may seem adequate, when looked at more they represent problematic species concepts. For example, the boundaries between related species become unclear with hybridisation, in a species complex of hundreds of similar microspecies, in a ring species. Among organisms that reproduce only asexually, the concept of a reproductive species breaks down, each clone is a microspecies. All species are given a two-part name, a "binomial"; the first part of a binomial is the genus.
The second part is called the specific epithet. For example, Boa constrictor is one of four species of the genus Boa. None of these is satisfactory definitions, but scientists and conservationists need a species definition which allows them to work, regardless of the theoretical difficulties. If species were fixed and distinct from one another, there would be no problem, but evolutionary processes cause species to change continually, to grade into one another. Species were seen from the time of Aristotle until the 18th century as fixed kinds that could be arranged in a hierarchy, the great chain of being. In the 19th century, biologists grasped. Charles Darwin's 1859 book The Origin of Species explained how species could arise by natural selection; that understanding was extended in the 20th century through genetics and population ecology. Genetic variability arises from mutations and recombination, while organisms themselves are mobile, leading to geographical isolation and genetic drift with varying selection pressures.
Genes can sometimes be exchanged between species by horizontal gene transfer. Viruses are a special case, driven by a balance of mutation and selection, can be treated as quasispecies. Biologists and taxonomists have made many attempts to define species, beginning from morphology and moving towards genetics. Early taxonomists such as Linnaeus had no option but to describe what they saw: this was formalised as the typological or morphological species concept. Ernst Mayr emphasised reproductive isolation, but this, like other species concepts, is hard or impossible to test. Biologists have tried to refine Mayr's definition with the recognition and cohesion concepts, among others. Many of the concepts are quite similar or overlap, so they are not easy to count: the biologist R. L. Mayden recorded about 24 concepts, the philosopher of science John Wilkins counted 26. Wilkins further grouped the species concepts into seven basic kinds of concepts: agamospecies for asexual organisms biospecies for reproductively isolated sexual organisms ecospecies based on ecological niches evolutionary species based on lineage genetic species based on gene pool morphospecies based on form or phenotype and taxonomic species, a species as determined by a taxonomist.
A typological species is a group of organisms in which individuals conform to certain fixed properties, so that pre-literate people recognise the same taxon as do modern taxonomists. The clusters of variations or phenotypes within specimens would differentiate the species; this method was used as a "classical" method of determining species, such as with Linnaeus early in evolutionary theory. However, different phenotypes are not different species. Species named in this manner are called morphospecies. In the 1970s, Robert R. Sokal, Theodore J. Crovello and Peter Sneath proposed a variation on this, a phenetic species, defined as a set of organisms with a similar phenotype to each other, but a different phenotype from other sets of organisms, it differs from the morphological species concept in including a numerical measure of distance or similarity to cluster entities based on multivariate comparisons of a reasonably large number of phenotypic traits. A mate-recognition species is a group of sexually reproducing organisms that recognize one another as potential mates.
Expanding on this to allow for post-mating isolation, a cohesion species is the most inclusive population of individuals having the potential for phenotypic cohesion through intrinsic cohesion mechanisms. A further development of the recognition concept is provided by the biosemiotic concept of species. In microbiology, genes can move even between distantly related bacteria extending to the whole bacterial domain; as a rule of thumb, microbiologists have assumed that kinds of Bacteria or Archaea with 16S ribosomal RNA gene sequences more similar than 97% to each other need to be checked by DNA-DNA hybridisation to decide if they belong to the same species or not. This concept was narrowed in 2006 to a similarity of 98.7%. DNA-DNA hybri
Asimina
Asimina is a genus of small trees or shrubs described as a genus in 1763. Asimina has large fruit, it collectively referred to as pawpaw. The genus includes the widespread common pawpaw Asimina triloba, which bears the largest edible fruit indigenous to the continent. Pawpaws are native to 26 states of the U. S. and to Ontario in Canada. The common pawpaw is a patch-forming understory tree found in well-drained, fertile bottomland and hilly upland habitat. Pawpaws are in the same plant family as the custard-apple, sweetsop and ylang-ylang; the genus name Asimina was first described and named by Michel Adanson, a French naturalist of Scottish descent. The name is adapted from the Native American name assimin through the French colonial asiminier; the common name pawpaw spelled paw paw, paw-paw, papaw derives from the Spanish papaya because of the superficial similarity of their fruits. Pawpaws are shrubs or small trees to 2–12 m tall; the northern, cold-tolerant common pawpaw is deciduous, while the southern species are evergreen.
The leaves are alternate, entire, 20–35 cm long and 10–15 cm broad. The flowers of pawpaws are in clusters of up to eight together; the petal color varies from white to red-brown. The fruit of the common pawpaw is a large edible berry, 5–16 cm long and 3–7 cm broad, weighing from 20–500 g, with numerous seeds, it has a flavor somewhat similar to both banana and mango, varying by cultivar, has more protein than most fruits. Accepted speciesAsimina angustifolia Raf. 1840 not A. Gray 1886. Florida and Georgia. Asimina longifolia Raf. - slimleaf pawpaw. Florida and Alabama. Asimina manasota DeLaney - manasota papaw native to two counties in Florida. - Florida and Georgia. Asimina obovata Nash) - flag-pawpaw or bigflower pawpaw - Florida Asimina parviflora Dunal - smallflower pawpaw. Southern states from Texas to Virginia. Asimina pygmaea Dunal - dwarf pawpaw. Florida and Georgia. Asimina reticulata Shuttlw. Ex Chapman - netted pawpaw. Florida and Georgia. Asimina spatulata D. B. Ward - slim leaf pawpaw. Florida and Alabama Not a valid species Asimina tetramera Small - fourpetal pawpaw.
Florida Asimina triloba Dunal - common pawpaw. Extreme southern Ontario and the eastern United States from New York west to southeast Nebraska, south to northern Florida and eastern Texas; the common pawpaw is native to shady, rich bottom lands, where it forms a dense undergrowth in the forest appearing as a patch or thicket of individual small slender trees. Pawpaw flowers are insect-pollinated, but fruit production is limited since few if any pollinators are attracted to the flower's faint, or sometimes non-existent scent; the flowers produce an odor similar to that of rotting meat to attract blowflies or carrion beetles for cross pollination. Other insects that are attracted to pawpaw plants include scavenging fruit flies, carrion flies and beetles; because of difficult pollination, some believe. Pawpaw fruit may be eaten by foxes, opossums and raccoons. However, pawpaw leaves and twigs are consumed by rabbits or deer; the leaves and bark of the common pawpaw tree contain natural insecticides known as acetogenins.
Larvae of the zebra swallowtail butterfly feed on young leaves of the various pawpaw species, but never occur in great numbers on the plants. Wild-collected fruits of the common pawpaw have long been a favorite treat throughout the tree's extensive native range in eastern North America. Fresh pawpaw fruits are eaten raw; the fruit pulp is often used locally in baked dessert recipes, with pawpaw substituted in many banana-based recipes. Pawpaws have never been cultivated for fruit on the scale of apples and peaches, but interest in pawpaw cultivation has increased in recent decades. However, only frozen fruit will ship well. Other methods of preservation include dehydration, production of jams or jellies, pressure canning; the pawpaw is gaining in popularity among backyard gardeners because of the tree's distinctive growth habit, the appeal of its fresh fruit, its low maintenance needs once established. The common pawpaw is of interest in ecological restoration plantings since this tree grows well in wet soil and has a strong tendency to form well-rooted clonal thickets.
The several other species of Asimina have few economic uses. The earliest documentation of pawpaws is in the 1541 report of the Spanish de Soto expedition, who found Native Americans cultivating it east of the Mississippi River. Chilled pawpaw fruit was a favorite dessert of George Washington, Thomas Jefferson planted it at his home in Virginia, Monticello; the Lewis and Clark Expedition sometimes subsisted on pawpaws during their travels. The common pawpaw was designated as the Ohio state native fruit in 2009. Flora of North America Asimina USDA distribution of Pawpaw Pawpaw Information from Kentuck
Cuba
Cuba the Republic of Cuba, is a country comprising the island of Cuba as well as Isla de la Juventud and several minor archipelagos. Cuba is located in the northern Caribbean where the Caribbean Sea, Gulf of Mexico and Atlantic Ocean meet, it is east of the Yucatán Peninsula, south of both the U. S. state of Florida and the Bahamas, west of Haiti and north of both Jamaica and the Cayman Islands. Havana is capital; the area of the Republic of Cuba is 110,860 square kilometres. The island of Cuba is the largest island in Cuba and in the Caribbean, with an area of 105,006 square kilometres, the second-most populous after Hispaniola, with over 11 million inhabitants; the territory, now Cuba was inhabited by the Ciboney Taíno people from the 4th millennium BC until Spanish colonisation in the 15th century. From the 15th century, it was a colony of Spain until the Spanish–American War of 1898, when Cuba was occupied by the United States and gained nominal independence as a de facto United States protectorate in 1902.
As a fragile republic, in 1940 Cuba attempted to strengthen its democratic system, but mounting political radicalization and social strife culminated in a coup and subsequent dictatorship under Fulgencio Batista in 1952. Open corruption and oppression under Batista's rule led to his ousting in January 1959 by the 26th of July Movement, which afterwards established communist rule under the leadership of Fidel Castro. Since 1965, the state has been governed by the Communist Party of Cuba; the country was a point of contention during the Cold War between the Soviet Union and the United States, a nuclear war nearly broke out during the Cuban Missile Crisis of 1962. Cuba is one of few Marxist–Leninist socialist states, where the role of the vanguard Communist Party is enshrined in the Constitution. Independent observers have accused the Cuban government of numerous human rights abuses, including arbitrary imprisonment. Culturally, Cuba is considered part of Latin America, it is a multiethnic country whose people and customs derive from diverse origins, including the aboriginal Taíno and Ciboney peoples, the long period of Spanish colonialism, the introduction of African slaves and a close relationship with the Soviet Union in the Cold War.
Cuba is a sovereign state and a founding member of the United Nations, the G77, the Non-Aligned Movement, the African and Pacific Group of States, ALBA and Organization of American States. The country is a middle power in world affairs, it has one of the world's only planned economies, its economy is dominated by the exports of sugar, tobacco and skilled labor. According to the Human Development Index, Cuba has high human development and is ranked the eighth highest in North America, though 67th in the world, it ranks in some metrics of national performance, including health care and education. It is the only country in the world to meet the conditions of sustainable development put forth by the WWF. Historians believe the name Cuba comes from the Taíno language, however "its exact derivation unknown"; the exact meaning of the name is unclear but it may be translated either as'where fertile land is abundant', or'great place'. Fringe theory writers who believe that Christopher Columbus was Portuguese state that Cuba was named by Columbus for the town of Cuba in the district of Beja in Portugal.
Before the arrival of the Spanish, Cuba was inhabited by three distinct tribes of indigenous peoples of the Americas. The Taíno, the Guanahatabey and the Ciboney people; the ancestors of the Ciboney migrated from the mainland of South America, with the earliest sites dated to 5,000 BP. The Taíno arrived from Hispanola sometime in the 3rd century A. D; when Columbus arrived they were the dominant culture in Cuba, having an estimated population of 150,000. The Taíno were farmers, while the Ciboney were farmers as well as hunter-gatherers. After first landing on an island called Guanahani, Bahamas, on 12 October 1492, Christopher Columbus commanded his three ships: La Pinta, La Niña and the Santa María, to land on Cuba's northeastern coast on 28 October 1492. Columbus claimed the island for the new Kingdom of Spain and named it Isla Juana after Juan, Prince of Asturias. In 1511, the first Spanish settlement was founded by Diego Velázquez de Cuéllar at Baracoa. Other towns soon followed, including San Cristobal de la Habana, founded in 1515, which became the capital.
The native Taíno were forced to work under the encomienda system, which resembled a feudal system in Medieval Europe. Within a century the indigenous people were wiped out due to multiple factors Eurasian infectious diseases, to which they had no natural resistance, aggravated by harsh conditions of the repressive colonial subjugation. In 1529, a measles outbreak in Cuba killed two-thirds of those few natives who had survived smallpox. On 18 May 1539, Conquistador Hernando de Soto departed from Havana at the head of some 600 followers into a vast expedition through the Southeastern United States, starting at La Florida, in search of gold, treasure and power. On 1 September 1548, Dr. Gonzalo Perez de Angulo was appointed governor of Cuba, he arrived in Santiago, Cuba on 4 November 1549 and declared the liberty of all natives. He became Cuba's first permanent governor to reside in Havana instead of Santiago, he built Havana's first church made of maso
Florida
Florida is the southernmost contiguous state in the United States. The state is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Atlantic Ocean, to the south by the Straits of Florida. Florida is the 22nd-most extensive, the 3rd-most populous, the 8th-most densely populated of the U. S. states. Jacksonville is the most populous municipality in the state and the largest city by area in the contiguous United States; the Miami metropolitan area is Florida's most populous urban area. Tallahassee is the state's capital. Florida's $1.0 trillion economy is the fourth largest in the United States. If it were a country, Florida would be the 16th largest economy in the world, the 58th most populous as of 2018. In 2017, Florida's per capita personal income was ranking 26th in the nation; the unemployment rate in September 2018 was 3.5% and ranked as the 18th in the United States. Florida exports nearly $55 billion in goods made in the 8th highest among all states.
The Miami Metropolitan Area is by far the largest urban economy in Florida and the 12th largest in the United States with a GDP of $344.9 billion as of 2017. This is more than twice the number of the next metro area, the Tampa Bay Area, which has a GDP of $145.3 billion. Florida is home to 51 of the world's billionaires with most of them residing in South Florida; the first European contact was made in 1513 by Spanish explorer Juan Ponce de León, who called it la Florida upon landing there in the Easter season, known in Spanish as Pascua Florida. Florida was a challenge for the European colonial powers before it gained statehood in the United States in 1845, it was a principal location of the Seminole Wars against the Native Americans, racial segregation after the American Civil War. Today, Florida is distinctive for its large Cuban expatriate community and high population growth, as well as for its increasing environmental issues; the state's economy relies on tourism and transportation, which developed in the late 19th century.
Florida is renowned for amusement parks, orange crops, winter vegetables, the Kennedy Space Center, as a popular destination for retirees. Florida is the flattest state in the United States. Lake Okeechobee is the largest freshwater lake in the U. S. state of Florida. Florida's close proximity to the ocean influences many aspects of daily life. Florida is a reflection of multiple inheritance. Florida has attracted many writers such as Marjorie Kinnan Rawlings, Ernest Hemingway and Tennessee Williams, continues to attract celebrities and athletes, it is internationally known for golf, auto racing, water sports. Several beaches in Florida have emerald-colored coastal waters. About two-thirds of Florida occupies a peninsula between the Gulf of the Atlantic Ocean. Florida has the longest coastline in the contiguous United States 1,350 miles, not including the contribution of the many barrier islands. Florida has a total of 4,510 islands; this is the second-highest number of islands of any state of the United States.
It is the only state that borders both the Gulf of the Atlantic Ocean. Much of the state is characterized by sedimentary soil. Florida has the lowest high point of any U. S. state. The climate varies from subtropical in the north to tropical in the south; the American alligator, American crocodile, American flamingo, Roseate spoonbill, Florida panther, bottlenose dolphin, manatee can be found in Everglades National Park in the southern part of the state. Along with Hawaii, Florida is one of only two states that has a tropical climate, is the only continental state with either a tropical climate or a coral reef; the Florida Reef is the only living coral barrier reef in the continental United States, the third-largest coral barrier reef system in the world. By the 16th century, the earliest time for which there is a historical record, major Native American groups included the Apalachee of the Florida Panhandle, the Timucua of northern and central Florida, the Ais of the central Atlantic coast, the Tocobaga of the Tampa Bay area, the Calusa of southwest Florida and the Tequesta of the southeastern coast.
Florida was the first region of the continental United States to be visited and settled by Europeans. The earliest known European explorers came with the Spanish conquistador Juan Ponce de León. Ponce de León spotted and landed on the peninsula on April 2, 1513, he named the region Florida. The story that he was searching for the Fountain of Youth is mythical and only appeared long after his death. In May 1539, Conquistador Hernando de Soto skirted the coast of Florida, searching for a deep harbor to land, he described seeing a thick wall of red mangroves spread mile after mile, some reaching as high as 70 feet, with intertwined and elevated roots making landing difficult. The Spanish introduced Christianity, horses, the Castilian language, more to Florida. Spain established several settlements with varying degrees of success. In 1559, Don Tristán de Luna y Arellano established a settlement at present-day Pensacola, making it the first attempted settlement in Florida, but it was abandoned by 1561.
In 1565, the settlement of St. Augustine was established under the leadership of admiral and
Soursop
Soursop is the fruit of Annona muricata, a broadleaf, evergreen tree. The exact origin is unknown, it is in the Annonaceae family. The soursop is adapted to areas of high humidity and warm winters; the fruit is no longer good for concentrate. With aroma similar to pineapple, the flavor of the fruit has been described as a combination of strawberries and apple, sour citrus flavor notes, contrasting with an underlying creamy texture reminiscent of coconut or banana. Soursop is promoted as an alternative cancer treatment, but there is no medical evidence it is effective for treating cancer or any disease. Annona muricata is a species of the genus Annona of the custard apple tree family, which has edible fruit; the fruit is called soursop due to its acidic taste when ripe. Annona muricata is native to the Caribbean and Central America but is now cultivated – and in some areas, becoming invasive – in tropical and subtropical climates throughout the world. Annona muricata is a small, evergreen tree that can grow to about 30 feet tall.
Its young branches are hairy. Leaves are oblong to oval, 8 centimetres to 16 centimetres long and 3 centimetres to 7 centimetres wide, they are a glossy dark green with no hairs above, paler and minutely hairy to no hairs below. The leaf stalks are 4 millimetres without hairs. Flower stalks are 2 millimetres to 5 millimetres woody, they appear opposite from the leaves or as an extra from near the leaf stalk, each with one or two flowers a third. Stalks for the individual flowers are stout and woody, minutely hairy to hairless and 15 millimetres to 20 millimetres with small bractlets nearer to the base which are densely hairy; the petals are yellowish. Outer petals meet at the edges without overlapping and are broadly ovate, 2.8 centimetres to 3.3 centimetres by 2.1 centimetres to 2.5 centimetres, tapering to a point with a heart shaped base. They are evenly thick, are covered with long, soft hairs externally and matted finely with soft hairs within. Inner petals are oval overlap, they measure 2.5 centimetres to 2.8 centimetres by 2 centimetres, are angled and tapering at the base.
Margins are comparatively thin, with fine matted soft hairs on both sides. The receptacle is hairy; the stamens are narrowly wedge-shaped. The connective-tip terminate abruptly and anther hollows are unequal. Sepals do not overlap. Carpels are basally growing from one base; the ovaries are covered with 1-ovuled, style short and stigma truncate. Its pollen is shed as permanent tetrads; the fruits are prickly. They can be up to 30 centimetres long, with a moderately firm texture, their flesh is juicy, acid and aromatic. The average weight of 1000 fresh seeds is 470 grams and they have an average oil content of 24%; when dried for 3 days at 60 °C, the average seed weight was 322 grams. They are tolerant of the moisture extraction, showing no problems for long-term storage under reasonable conditions. Annona muricata is tolerant of poor soil and prefers lowland areas between the altitudes of 0 to 1,200 metres, it cannot stand frost. The exact origin is unknown, it is an introduced species on all temperate continents in subtropical regions.
The plant is grown for its 20–30 cm long, green fruit, which can have a mass of up to 6.8 kg, making it the second biggest annona after the junglesop. Away from its native area, some limited production occurs as far north as southern Florida within USDA Zone 10, it is grown in parts of Southeast Asia and is abundant on the Island of Mauritius. The main suppliers of the fruit are Mexico followed by Peru, Ecuador and Haiti; the flesh of the fruit consists of an edible, white pulp, some fiber, a core of indigestible black seeds. The pulp is used to make fruit nectar, fruit juice drinks, as well as candies and ice cream flavorings. Due to the fruit's widespread cultivation, its derivative products are consumed in many countries like Mexico, Venezuela and Fiji; the seeds are left in the preparation, removed while consuming, unless a blender is used for processing. In Indonesia, dodol sirsak, a sweetmeat, is made by boiling soursop pulp in water and adding sugar until the mixture hardens. Soursop is a common ingredient for making fresh fruit juices that are sold by street food vendors.
In the Philippines, it is called guyabano, derived from the Spanish guanábana, is eaten ripe, or used to make juices, smoothies, or ice cream. Sometimes, they use the leaf in tenderizing meat. In Vietnam, this fruit is called mãng cầu Xiêm in the south, or mãng cầu in the north, is used to make smoothies, or eaten as is. In Cambodia, this fruit is called tearb barung "western custa
Magnoliids
Magnoliids are a group of flowering plants. Until the group included about 9,000 species, including magnolias, bay laurel, avocado, black pepper, tulip tree and many others; that group is characterized by trimerous flowers, pollen with one pore, branching-veined leaves. "Magnoliidae" is the botanical name of a subclass, "magnoliids" is an informal name that does not conform to the International Code of Nomenclature for algae and plants. The circumscription of a subclass will vary with the taxonomic system being used; the only requirement is. The informal name "magnoliids" is used by some researchers to avoid the confusion that surrounds the name "Magnoliidae". More the group has been redefined under the PhyloCode as a node-based clade comprising the Canellales, Laurales and Piperales. Chase & Reveal have proposed, "Magnoliidae" as the name used for the entire group of flowering plants, the formal name "Magnolianae" for the group of four orders are discussed here; the APG III and its predecessor systems did not use formal botanical names above the rank of order.
Under those systems, larger clades were referred to by informal names, such as "magnoliids" or "magnoliid complex". The formal name in Linnean nomenclature was specified in a separate APG publication as the existing name "Magnolianae" Takht.. The APG III recognizes a clade within the angiosperms for the magnoliids; the circumscription is: The clade includes most of the basal groups of the angiosperms. This clade was formally named Magnoliidae in 2007 under provisions of the PhyloCode; the Cronquist system used the name Magnoliidae for one of six subclasses. In the original version of this system the circumscription was: Subclass Magnoliidae: Order Aristolochiales Order Illiciales Order Laurales Order Magnoliales Order Nymphaeales Order Papaverales Order Piperales Order Ranunculales Both Dahlgren and Thorne classified the magnoliids in superorder Magnolianae, rather than as a subclass. In their systems, the name Magnoliidae is used for a much larger group including all dicotyledons; this is the case in some of the systems derived from the Cronquist system.
Dahlgren divided his Magnolianae into ten orders, more than other systems of the time, unlike Cronquist and Thorne, he did not include the Piperales. Thorne grouped most of his Magnolianae into two large orders and Berberidales, although his Magnoliales was divided into suborders along lines similar to the ordinal groupings used by both Cronquist and Dahlgren. Thorne revised his system in 2000, restricting the name Magnoliidae to include only the Magnolianae and Rafflesianae, removing the Berberidales and other included groups to his subclass Ranunculidae; this revised system diverges from the Cronquist system, but agrees more with the circumscription published under APG II. Comparison of classification systems is difficult. Two authors may apply the same name to groups with different composition of members. Two authors may describe the same group with nearly identical composition, but each may apply a different name to that group or place the group at a different taxonomic rank. For example, the composition of Cronquist's subclass Magnoliidae is nearly the same as Thorne's superorder Magnolianae, despite the difference in taxonomic rank.
Because of these difficulties and others, the synoptic table below imprecisely compares the definition of "magnoliid" groups in the systems of four authors. For each system, only orders are named in the table. All orders included by a particular author are linked in that column; when a taxon is not included by that author, but was included by an author in another column, that item appears in unlinked italics and indicates remote placement. The sequence of each system has been altered from its publication in order to pair corresponding taxa between columns; the magnoliids is a large group of plants, with many species that are economically important as food, perfumes, as ornamentals, among many other uses. One cultivated magnoliid fruit is the avocado, believed to have been cultivated in Mexico and Central America for nearly 10,000 years. Now grown throughout the American tropics, it originates from the Chiapas region of Mexico or Guatemala, where "wild" avocados may still be found; the soft pulp of the fruit is eaten mashed into guacamole.
The ancient peoples of Central America were the first to cultivate several fruit-bearing species of Annona. These include the custard-apple, sweetsop or sugar-apple, the cherimoya. Both soursop and sweetsop now are grown for their fruits in the Old World as well; some members of the magnoliids have served as important food additives. Oil of sassafras was used as a key flavoring in both root beer and in sarsaparilla; the primary ingredient responsible for the oil's flavor is safrole, but it is no longer used in either the United States or Canada. Both nations banned the use of safrole as a food additive in 1960 as a result of studies that demonstrated safrole promoted liver damage and tumors in mice. Consumption of more than a minute quantity of the oil causes nausea, vomiting and shallow rapid breathing, it is toxic, can damage the kidneys. In addition to its former use as a food additive, safro
Deciduous
In the fields of horticulture and botany, the term deciduous means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves in the autumn. The term deciduous means "the dropping of a part, no longer needed" and the "falling away after its purpose is finished". In plants, it is the result of natural processes. "Deciduous" has a similar meaning when referring to animal parts, such as deciduous antlers in deer, deciduous teeth in some mammals. Wood from deciduous trees is used in a variety of ways in several industries including lumber for furniture and flooring, bowling pins and baseball bats and furniture, cabinets and paneling. In botany and horticulture, deciduous plants, including trees and herbaceous perennials, are those that lose all of their leaves for part of the year; this process is called abscission. In some cases leaf loss coincides with winter -- namely in polar climates. In other parts of the world, including tropical and arid regions, plants lose their leaves during the dry season or other seasons, depending on variations in rainfall.
The converse of deciduous is evergreen, where foliage is shed on a different schedule from deciduous trees, therefore appearing to remain green year round. Plants that are intermediate may be called semi-deciduous. Other plants are semi-evergreen and lose their leaves before the next growing season, retaining some during winter or dry periods; some trees, including a few species of oak, have desiccated leaves that remain on the tree through winter. Many deciduous plants flower during the period when they are leafless, as this increases the effectiveness of pollination; the absence of leaves improves wind transmission of pollen for wind-pollinated plants and increases the visibility of the flowers to insects in insect-pollinated plants. This strategy is not without risks, as the flowers can be damaged by frost or, in dry season regions, result in water stress on the plant. There is much less branch and trunk breakage from glaze ice storms when leafless, plants can reduce water loss due to the reduction in availability of liquid water during cold winter days.
Leaf drop or abscission involves complex physiological changes within plants. The process of photosynthesis degrades the supply of chlorophylls in foliage; when autumn arrives and the days are shorter or when plants are drought-stressed, deciduous trees decrease chlorophyll pigment production, allowing other pigments present in the leaf to become apparent, resulting in non-green colored foliage. The brightest leaf colors are produced when days grow short and nights are cool, but remain above freezing; these other pigments include carotenoids that are yellow and orange. Anthocyanin pigments produce red and purple colors, though they are not always present in the leaves. Rather, they are produced in the foliage in late summer, when sugars are trapped in the leaves after the process of abscission begins. Parts of the world that have showy displays of bright autumn colors are limited to locations where days become short and nights are cool. In other parts of the world, the leaves of deciduous trees fall off without turning the bright colors produced from the accumulation of anthocyanin pigments.
The beginnings of leaf drop starts when an abscission layer is formed between the leaf petiole and the stem. This layer is formed in the spring during active new growth of the leaf; the cells are sensitive to a plant hormone called auxin, produced by the leaf and other parts of the plant. When auxin coming from the leaf is produced at a rate consistent with that from the body of the plant, the cells of the abscission layer remain connected; the elongation of these cells break the connection between the different cell layers, allowing the leaf to break away from the plant. It forms a layer that seals the break, so the plant does not lose sap. A number of deciduous plants remove nitrogen and carbon from the foliage before they are shed and store them in the form of proteins in the vacuoles of parenchyma cells in the roots and the inner bark. In the spring, these proteins are used as a nitrogen source during the growth of new leaves or flowers. Plants with deciduous foliage have advantages and disadvantages compared to plants with evergreen foliage.
Since deciduous plants lose their leaves to conserve water or to better survive winter weather conditions, they must regrow new foliage during the next suitable growing season. Evergreens suffer greater water loss during the winter and they can experience greater predation pressure when small. Losing leaves in winter may reduce damage from insects. Removing leaves reduces cavitation which can damage xylem vessels in plants; this allows deciduous plants to have xylem vessels with larger diameters and therefore a greater rate of transpiration during the summer growth period
Media related to Annona at Wikimedia Commons
Data related to Annona at Wikispecies
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