The Cimbrian or Cimbric War (113–101 BC) was fought between the Roman Republic and the Germanic and Celtic tribes of the Cimbri and the Teutons, Ambrones and Tigurini, who migrated from the Jutland peninsula into Roman-controlled territory, and clashed with Rome and her allies. The Cimbrian War was the first time since the Second Punic War that Italia and Rome itself had been seriously threatened.

The timing of the war had a great effect on the internal politics of Rome, and the organization of its military. The war contributed greatly to the political career of Gaius Marius, whose consulships and political conflicts challenged many of the Roman Republic's political institutions and customs of the time. The Cimbrian threat, along with the Jugurthine War, allegedly inspired the putative Marian reforms of the Roman legions, a view now contested by modern historians.

Rome was finally victorious, and its Germanic adversaries, who had inflicted on the Roman armies the heaviest losses that they had suffered since the Second Punic War, with victories at the battles of Arausio and Noreia, were left almost completely annihilated after Roman victories at Aquae Sextiae and Vercellae. Some of the surviving captives are reported to have been among the rebelling gladiators during the Third Servile War.

Migrations and conflicts
According to some Roman accounts, sometime around 120–115 BC, the Cimbri left their original lands around the North Sea due to flooding (Strabo, on the other hand, wrote that this was unlikely or impossible) They supposedly journeyed to the south-east and were soon joined by their neighbours and possible relatives the Teutones. Together they defeated the Scordisci, along with the Boii, many of whom apparently joined them. In 113 BC they arrived on the Danube, in Noricum, home to the Roman-allied Taurisci. Unable to hold back these new, powerful invaders on their own, the Taurisci called on Rome for aid.

Initial Roman defeats
The following year the Roman consul Gnaeus Papirius Carbo led the legions into Noricum, and after making a show of force, took up a strong defensive position and demanded that the Cimbri and their allies leave the province immediately. The Cimbri initially set about complying peacefully with Rome's demands, but soon discovered that Carbo had laid an ambush against them. Infuriated by this treachery, they attacked and, at the Battle of Noreia, annihilated Carbo's army, almost killing Carbo in the process.

Italy was now open to invasion, yet for some reason, the Cimbri and their allies moved west over the Alps and into Gaul. In 109 BC, they invaded the Roman province of Gallia Narbonensis and defeated the Roman army there under Marcus Junius Silanus. In 107 BC, the Romans were defeated again, this time by the Tigurini, who were allies of the Cimbri whom they had met on their way through the Alps. That same year, they defeated another Roman army at the Battle of Burdigala (modern day Bordeaux) and killed its commander, the consul Lucius Cassius Longinus Ravalla.

Disaster at Arausio
In 105 BC, Rome and its new consul Gnaeus Mallius Maximus and the proconsul Quintus Servilius Caepio, in order to settle the matter once and for all, gathered the largest force it had fielded since the Second Punic War, and possibly the largest force it had ever sent to battle. The force consisted of over 80,000 men, along with tens of thousands of support personnel and camp followers in two armies, one led by each consul.

The consuls led their armies on their own armed migration to the Rhône River near Orange, Vaucluse, where, disliking and distrusting each other, they erected separate camps on opposite sides of the river; by so doing they left their disunited force open to separate attack. The overconfident Caepio foolishly attacked without support from Maximus; his legions were wiped out and his undefended camp overrun. The now isolated and demoralized troops of Maximus were then easily defeated. Thousands more were slain trying desperately to rally and defend his poorly positioned camp. Only Caepio, Maximus, and a few hundred Romans escaped with their lives across the carnage-choked river. The Battle of Arausio was the costliest defeat Rome had suffered since Cannae and, in fact, the losses and long-term consequences were far greater. For the Cimbri and Teutones it was a great (though temporary) triumph.

Instead of immediately gathering their allies and marching on Rome, the Cimbri proceeded to Hispania. There, they suffered their first defeat, not at the hands of a Roman army, but against a Celtiberian coalition. In the meantime, the Teutones remained in Gaul. Why they again failed to invade Italy remains a mystery. Theodor Mommsen speculatively describes their methods of war:

Marius takes command

Following the devastation of the Arausio, fear shook the Roman Republic to its foundations. The terror cimbricus became a watchword, as Rome expected the Cimbri at its gates at any time. In this atmosphere of panic and desperation, an emergency was declared. The constitution was ignored and Gaius Marius, the victor over Jugurtha of Numidia was elected consul for an unprecedented, and arguably illegal, five years in a row, starting in 104 BC. Because of the destruction of the Roman force at Arausio and the pressure of the impending crisis, Marius was tasked with rebuilding, effectively from scratch, the Gallic legions. Building his army around a core of trained legionaries from the last year, Marius again secured exemption from the property requirements and with his newly minted reputation for victory, raised an army of some thirty thousand Romans and forty thousand Italian allies and auxiliaries. He established a base around the town of Aquae Sextiae (modern Aix-en-Provence) and trained his men. Over his successive consulships, Marius was not idle. He trained his troops, built his intelligence network, and conducted diplomacy with the Gallic tribes on the provincial frontiers.

While the panicked Senate and people of Rome gave Marius the power he needed to build his army, the failure of the Cimbri and Teutones to follow up on their victory gave him the time he needed to finish it. They would soon be confronted by an army of organized and trained soldiers under the leadership of a brilliant and ruthless commander.

Turning point
By 102 BC, Marius was ready to face the Cimbri; the latter, after difficulties in Spain, had turned north into Gaul, where they were joined by the Teutons. After this union, the Germanic coalition determined to move back south upon Italy, which they had previously avoided. Marching south through Switzerland and Savoy, their army was augmented by some tribes of Helvetians, particularly the Tigurini, and the Ambrones of uncertain descent. Before approaching Italy, the Germans decided on a two-pronged movement; the Teutons with the Ambrones and the Tigurini would move from the west along the coast-road from Transalpine into Cisalpine Gaul; while the Cimbri would march east and turn around into Italy by the Julian and Carnic Alps. When Marius heard of their movements, he advanced to Valence, and established his camp at the confluence of the Isère and the Rhône, where he could observe and halt the march of the Teutons. When the Teutons arrived, they attempted to force him into battle, but he declined; they attacked the Roman camp, but were beaten off. Impatient of the delay and of Marius' passivity, they finally decided to simply march past him into Italy. So enormous were their numbers, that they reportedly took 6 whole days marching by his camp, and in their arrogance they taunted the Romans, what message they wished them to give to their wives?  Marius followed cautiously, maintaining distance from the enemy, but closely following his movements. A few days later, a skirmish turned into a battle with the Ambrones, who for some reason camped separately from the Teutones. The Ambrones were defeated with heavy losses and fled to their Teutonic allies. The Teutones halted their trek south and awaited Marius near Aquae Sextiae. This afforded Marius favorable conditions, for with his enemy stationary he got to scout the battlegrounds and he chose his ground carefully. In the subsequent battle, he lured the Teutones and their allies into attacking him while his army was occupying the high ground. During their attack they were ambushed from the rear by a select force of five cohorts which Marius had hidden in a nearby wood. The Teutones were routed and massacred and their king, Teutobod, was placed in Roman chains. But Aquae Sextiae had only evened the score: while the Teutones had been eliminated, the Cimbri remained a formidable threat.

In 101 BC, the Cimbri returned to Gaul and prepared for the final stage of their struggle with Rome. For the first time they penetrated through the Alpine passes, which Marius's co-consul for that year, Quintus Lutatius Catulus, had failed to fortify, into northern Italy. Catulus withdrew behind the Po River, leaving the countryside open to the invaders. But the Cimbri took their time ravishing the fertile region, which gave Marius time to arrive with reinforcements—his same victorious legions from Aquae Sextiae. It would be at Vercellae near the confluence of the Sesia River with the Po on the Raudine Plain where the superiority of the new Roman legions and their cavalry were clearly demonstrated. In the devastating defeat the Cimbri were virtually annihilated, and both their highest leaders, Boiorix and Lugius, fell. The women killed both themselves and their children in order to avoid slavery. Thus the war, which began with a mass migration, ended in defeat and mass suicide.

Aftermath

The Cimbri were not completely wiped off the face of the map or from the pages of history. Their allies, the Boii, with whom they intermixed, settled in southern Gaul and Germania and were there to welcome and confront Julius Caesar,  Marius's nephew, in his campaigns of conquest. Some of the surviving captives are reported to have been among the rebelling gladiators in the Third Servile War.

The political consequences from the war had an immediate and lasting impact on Rome. The end of the Cimbrian war marked the beginning of the rivalry between Marius and Sulla, which eventually led to the first of Rome's great civil wars. Moreover, following the final victory at Vercellae, and without first asking permission from the Senate, Marius granted Roman citizenship to two cohorts of his Italian allied soldiers (around a thousand soldiers, within an army counting about 32 000 men, half of which were Italian allies), allegedly claiming that in the din of battle he could not distinguish between the voices of Romans and the Italic allies.

According to traditional historiography, henceforth Italian legions became Roman legions and the allied cities of the Italian peninsula progressively began to demand a greater say in the external policy of the Republic, leading eventually to the Social War.

References

 Dupuy, R. Ernest, and Trevor N. Dupuy, The Encyclopedia Of Military History: From 3500 B.C. To The Present. (2nd Revised Edition 1986) pp. 90–91.

 Mommsen, Theodor, History of Rome, Book IV "The Revolution", pp. 66–72.

110s BC conflicts
100s BC conflicts
2nd century BC in the Roman Republic
Wars involving the Roman Republic
Wars involving Germanic peoples
Wars involving the Celts

Cimbrian War


Oromia Bank (OB) is a private bank based in Addis Ababa, Ethiopia. It was established on 18 September 2008.

Overview
Oromia Bank S.C began operation on 25 October 2008 with a starting capital of 110 million birr (Br), surpassing the minimum capital requirement by 35 million Br. With its headquarters located in front of Dembel City Centre, near Getu Commercial Center in its own 13 story building on Africa Avenue (Bole Road).

Established with the commercial banking business objectives, OIB is undertaking a universal commercial banking services such as deposit mobilization, lending of money, remittance service, and international banking services and interest free banking. The Bank has now launched Electronic banking systems such as Card banking known as Oro-Card (ATM and POS), Mobile Banking named as Oro-Cash, Agent Banking-Oro Agent and Internet banking namely Oro-Click. The number of OIB branches have now reached 225 throughout Ethiopia all connected by core banking system. The Bank is now one of the most influential and popular private banks in Ethiopia and also known for pioneering Interest free banking services.

References

External links

Banks of Ethiopia
Banks established in 2008
Oromia Region
Companies based in Addis Ababa
2008 establishments in Ethiopia

Oromia International Bank


Johan Georg Lillienberg (1713 – 26 April 1798) was a Swedish count and politician who was appointed as Lawspeaker of Gotland in 1746. In 1749, he became Governor of Åbo and Björneborg, and in 1757 Governor of Uppsala County. Lillienberg was made a baron in 1766 and a count in 1778.

In 1768, Lillienberg was elected a member of the Royal Swedish Academy of Sciences.

He died at his manor Herresta in Södermanland.

1713 births
1798 deaths
Swedish nobility
Members of the Royal Swedish Academy of Sciences
Governors of Uppsala County

Johan Georg Lillienberg


The Solar Hijri calendar is the official calendar of Iran. It is only used in Iran and Afghanistan. The name of the calendar is abbreviated as SH. It is also called the Solar Hejri calendar and (; ).

Its year begins on the March equinox (Nowruz) at the Iranian standard meridian (52.5°E, UTC+03:30). Each year is 365 or 366 days long.

Each of the twelve months corresponds with a zodiac sign. The first six months have 31 days, the next five have 30 days, and the last month has 29 days in usual years but 30 days in leap years. Its New Year's Day (1 Nowruz) always falls on the March equinox.

References

Calendars
Persian culture
Afghan society and culture

Solar Hijri Calendar


Variable compression ratio (VCR) is a technology to adjust the compression ratio of an internal combustion engine while the engine is in operation. This is done to increase fuel efficiency while under varying loads. Variable compression engines allow the volume above the piston at top dead centre to be changed. Higher loads require lower ratios to increase power, while lower loads need higher ratios to increase efficiency, i.e. to lower fuel consumption.  For automotive use this needs to be done as the engine is running in response to the load and driving demands. The 2019 Infiniti QX50 is the first commercially available vehicle that uses a variable compression ratio engine.

Advantages
Gasoline engines have a limit on the maximum pressure during the compression stroke, after which the fuel/air mixture detonates rather than burns. To achieve higher power outputs at the same speed, more fuel must be burned and therefore more air is needed. To achieve this, turbochargers or superchargers are used to increase the inlet pressure. This would result in detonation of the fuel/air mixture unless the compression ratio was decreased, i.e. the volume above the piston made greater. This can be done to a greater or lesser extent with massive increases in power being possible. The down side of this is that under light loading, the engine can lack power and torque. The solution is to be able to vary the inlet pressure and adjust the compression ratio to suit. This gives the best of both worlds, a small efficient engine capable of great power on demand. In addition, VCR allows free use of different fuels besides petrol e.g. LPG or ethanol .

Cylinder displacement is altered by using a hydraulic system connected to the crankshaft, and adjusted according to the load and acceleration required.

Production
Variable compression engines have existed for decades but only in laboratories for the purposes of studying combustion processes. These designs usually have a second adjustable piston set in the head opposing the working piston.

In 2018 Infiniti began production of their variable compression turbo engine, which uses a mechanical linkage to achieve the variability. It was installed in their QX50 SUV. The engine can produce any compression ratio from 8:1 to 14:1.  The highest torque is achieved at 8:1, giving high acceleration, while the best gas mileage (fuel efficiency) is achieved at 14:1. The electronic engine controller responds to the pressure on the gas pedal, in real-time, altering the compression ratio seamlessly. Although this engine has a displacement of 2.0 L, and is an inline-four engine, it does not use balance shafts to eliminate the secondary vibrations. It is inherently balanced by the mechanical linkage.

Two-stroke engines
Due to the comparative simplicity of cylinder head design (lacking intake valves) it is somewhat easier to implement in two-stroke engines. From the late 90s on up models which expand on this idea have been available, such as from Yamaha, which dynamically vary the size of the combustion chamber. As of late (in the 2000s) this technology has seen some renewed interest, due it being able to burn a wide range of fuels (e.g. including alcohols) such as the Lotus Omnivore.

A much earlier commercialized two-stroke engine, but very small (18 cc) and not powerful enough to be very successful, was the Lohmann engine produced in the early 1950s as a retrofit engine for bicycles .  This engine had a one-piece cylinder head and sleeve, whose distance from the crankshaft was adjusted by a jackscrew operated by cables from a twist grip on the handlebar.  Compression adjustment was essential to the operation of this engine because it used compression ignition of a fuel mixture which was introduced prior to the compression stroke and which therefore ignited whenever the compression brought it to a sufficient temperature.  This meant that the compression needed would vary with air temperature, engine temperature, and fuel type: with too much compression the engine would suffer premature ignition and with too little it would fail to ignite at all.  Thus the operator had to adjust the compression continually as operating conditions varied.  The Lohmann engine was produced for only about five years because the control of compression (simultaneously with fuel flow) required considerable practice, and because even at optimal adjustment it provided no more power than a moderately fit rider could provide without assistance.

Engine designs
The first VCR engine built and tested was by Harry Ricardo in the 1920s. This work led to him devising the octane rating system that is still in use today. Many companies have been undertaking their own research into VCR Engines, including Saab, Nissan, Volvo, PSA/Peugeot-Citroën and Renault. The 2019 Infiniti QX50 is available with a production version of the turbocharged variable compression engine.

Peugeot MCE-5

The Peugeot design works by varying the effective length of the con-rods connecting the piston to the crank. When the con-rod is shorter, the compression ratio is lower and vice versa. On the left hand-side of the diagram is the conventional piston of an internal combustion engine. On the right is an hydraulic cylinder with double-acting piston. This acts through a rod-crank system with a gear wheel, whose movement adjusts the effective con-rod length and thus the compression ratio in the left cylinder.

Saab SVC
SAAB Automobile rekindled interest in variable compression when they introduced their SVC engine to the world at the Geneva motor show in 2000. SAAB had been involved in working with the 'Office of Advanced Automotive Technologies', to produce a modern petrol VCR engine that showed an efficiency comparable with that of a Diesel. The SAAB SVC was an advanced and workable addition to the world of VCR engines, but it never reached production due to the company's bankruptcy in 2016.

The design, an implementation of the Larsen VCR engine, consisted of a monobloc head, which contained all of the valve gear, and the crankshaft/crankcase assembly. These parts were connected by a pivot which allowed 4 degrees of movement controlled by a hydraulic actuator. This mechanism allows the distance between the crankshaft centre line and the cylinder crown to be varied. Unlike the Peugeot design, the effective connecting rod length is fixed.
A supercharger was chosen in preference to a turbocharger to achieve the necessary response time and high boost pressure.

To alter Vc, the SVC 'lowers' the cylinder head closer to the crankshaft. It does this by replacing the typical one-part engine block with a two-part unit, with the crankshaft in the lower block and the cylinders in the upper portion. The two blocks are hinged together at one side (imagine a book, lying flat on a table, with the front cover held an inch or so above the title page). By pivoting the upper block around the hinge point, the Vc (imagine the air between the front cover of the book and the title page) can be modified. In practice, the SVC adjusts the upper block through a small range of motion, using a hydraulic actuator.

See also
 Continuously variable transmission
 DiesOtto
 Miller cycle
 Variable valve timing
 Infiniti VC-T - First Variable Compression Engine - Road & Track

References

 Waulis Patent Application
 Saab press release
 Automotive engineering international article
 Infiniti Introduces the First Production Engine With Variable Compression

Engine technology
Two-stroke engine technology

Variable compression ratio


A hesternal tense (abbreviated ) is a past tense for the previous day. (Hesterno die is Latin for 'yesterday'.)

Hesternal tense refers to an event which occurred yesterday (in an absolute tense system) or on the preceding day (in a relative tense system). A pre-hesternal tense refers to an event which occurred prior to yesterday or the previous day. Hesternal tense is reported, for example in the Fyam or Fyem language of northern Nigeria.

Hesternal tense may also be used to denote a tense for any time prior to the current day – that is, to mean pre-hodiernal.

References

Grammatical tenses

Hesternal tense


The Yamacraw were a Native American tribe that emerged in the early 18th century, occupying parts of what became Georgia, specifically along the bluffs near the mouth of the Savannah River where it enters the Atlantic Ocean.  They were made up of Lower Creek and Yamasee, and remained independent for about 20 years before integrating again with the main part of the Lower Creek people. This area was later developed as the city of Savannah.

History
The Yamacraw tribe was formed in the late 1720s by leader Tomochichi from some bands of Yamasee and Lower Creek people who had disagreed with the severing of friendship with the British during the Yamasee War of 1715. By 1728 the Yamacraw had settled along the Savannah River near its mouth. This was later developed as the present-day city of Savannah. In 1733 James Oglethorpe, interested in founding a colony at the site because of its strategic location on the water, negotiated with Tomochichi and the Yamacraw agreed to move their village upriver.

A mid-19th century history of Tomochichi noted dissension over the status of this name and people. Charles Colcock Jones wrote that the Creek did not acknowledge any people known as the Yamacraw. Also he said that neither the Maskoki (Muskogee) nor Yuchi dialects of the region used the "r" in such a way as in that name.

References

Further reading
David H. Corkran, The Creek Frontier, 1540-1783 (Norman: University of Oklahoma Press, [1967]).
John R. Swanton, Early History of the Creek Indians and Their Neighbors (Washington, D.C.: Government Printing Office, 1922; reprint, Gainesville: University Press of Florida, 1998).

External links
Yamacraw Indian information
Georgia.gov information on the Yamacraw

Native American tribes in Georgia (U.S. state)
History of Savannah, Georgia

Yamacraw


Horace Elgin Dodge Sr. (May 17, 1868 – December 10, 1920) was an American automobile manufacturing pioneer and co-founder of Dodge Brothers Company.

Early years and business
He was born in Niles, Michigan, on May 17, 1868. His father owned a foundry and machine shop. Horace Dodge and his elder brother John Francis Dodge were inseparable as children and as adults. In 1886, the Dodge brothers moved to Detroit, Michigan, where they took jobs at a boilermaker plant. In 1894, they went to work as machinists at the Canadian Typograph Company across the Detroit River in Windsor, Ontario.

In 1896, Horace Dodge married Anna Thompson, a Scottish immigrant born in Dundee. The couple had a son, Horace Jr., and a daughter, Delphine. Thompson later married actor Hugh Dillman after the death of Dodge.

While brother John Dodge was the sales-oriented managerial type, Horace was a gifted mechanic and inveterate tinkerer. He invented the first dirt-proof ball bearing; in 1897, John arranged a deal for them to join with a third-party investor to manufacture bicycles. Within a few years, they sold the business and, in 1901, used the proceeds of the sale to set up their own machine shop in Detroit. During their first year in business, the Dodge brothers' company began making parts for the automobile industry.

Automobiles
In 1902, they won a contract to build transmissions for the Olds Motor Vehicle Company upon which they built a solid reputation for quality and service. However, the following year they turned down a second contract from Olds (Oldsmobile) to retool their plant to build engines for Henry Ford in a deal that included a share position in the new Ford Motor Company. They had invested in Ford's business and eventually Ford would be in debt to the Dodge Brothers. By 1910, Horace Dodge and his brother were so successful they built a new plant in Hamtramck, Michigan.

For ten years, the Dodge brothers' company was supplier to Ford, and John Dodge worked as vice president of the Ford company. In 1913 the Dodge brothers terminated their Ford contract and devoted their energies toward producing a Dodge automobile. They introduced the Dodge Brothers 30 in November, 1914. They began building motor trucks, ambulances and other vehicles for the United States military during the arms buildup for World War I At war's end, their company manufactured and marketed both cars and trucks.

He was inducted into the Automotive Hall of Fame in 1981.

Personal life
Despite their wealth and growing influence in the business community, the red-haired  Dodge brothers' crude manners and aggressive conduct made them socially unacceptable to most of the wealthy Detroit elite. In 1912, Horace Dodge built a red sandstone mansion in Grosse Pointe called Rose Terrace. The huge home with formal gardens and boat dock overlooked Lake St. Clair.

This was replaced by a second Rose Terrace, constructed in the 1930s by architect Horace Trumbauer, for Mrs. Dodge and her second husband. Architectural historian W. Hawkins Ferry described the mansion as "unquestionably Grosse Pointe's most regal residence". In addition to Rose Terrace, the Dodges acquired a large winter estate in Palm Beach, Florida. Horace's wife Anna had studied music, and this fact won them acceptance by the city's social order. Horace and Anna Dodge became major benefactors of the new Detroit Symphony Orchestra and would play a key role in the construction of Orchestra Hall.

A speedboat and yachting enthusiast, Horace Dodge's keen interest in the vessel's engines led him to establish a marine division as part of their automotive business. He purchased several steam yachts, each larger and more luxurious than the previous. The first two large yachts were named Nokomis, both being purchased by the government for World War I use, with the second being described as a "floating palace" even as it was being stripped for Navy use shortly after completion. The last, named the Delphine for his daughter after following the Nokomis tradition in the early phase of design, was a  vessel. Construction commenced in 1920 and was completed in 1921, after his death. In the ensuing years the yacht experienced a sinking, a run onto rocks, and service as a United States Navy patrol boat during World War II. The Delphine passed through the hands of several owners and after major refurbishing it sails the Mediterranean today as a luxury charter.

Death

In 1919, Henry Ford bought out the Dodge brothers' shareholdings in Ford Motor Company for $25 million. In January 1920, Horace's brother, John, died during the influenza epidemic. He was interred in the family's Egyptian-style mausoleum in Detroit's Woodlawn Cemetery guarded by two Sphinx statues. Having also contracted the flu that December following several relapses, Horace also died from complications of the disease resulting in pneumonia and cirrhosis of the liver at the age of 52 in Palm Beach, Florida. He was interred with his brother in the same mausoleum. His widow outlived him by fifty years.

In 1925, Horace and John Dodge's widows sold their automobile business to Dillon Read investment bankers for $146 million. Upon her death in 1970, Anna Thompson Dodge left a sum to the City of Detroit for the construction of the Horace E. Dodge and Son Memorial Fountain. The fountain was designed by sculptor Isamu Noguchi and opened in 1978 as part of the city's Hart Plaza. Horace E. Dodge Jr. died in 1963 at age 63.

References

External links

Story & photos of the Delphine II yacht

1868 births
1920 deaths
American philanthropists
American founders of automobile manufacturers
American automotive pioneers
Businesspeople from Detroit
People from Niles, Michigan
Deaths from the Spanish flu pandemic in Florida
Machinists
American boilermakers
Dodge family
Burials at Woodlawn Cemetery (Detroit)
Deaths from cirrhosis
Alcohol-related deaths in Florida
Deaths from pneumonia in Florida

Horace Elgin Dodge


Plants are the eukaryotes that form the kingdom Plantae; they are predominantly photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with cyanobacteria to produce sugars from carbon dioxide and water, using the green pigment chlorophyll. Exceptions are parasitic plants that have lost the genes for chlorophyll and photosynthesis, and obtain their energy from other plants or fungi.

Historically, as in Aristotle's biology, the plant kingdom encompassed all living things that were not animals, and included algae and fungi. Definitions have narrowed since then; current definitions exclude the fungi and some of the algae. By the definition used in this article, plants form the clade Viridiplantae (green plants), which consists of the green algae and the embryophytes or land plants (hornworts, liverworts, mosses, lycophytes, ferns, conifers and other gymnosperms, and flowering plants). A definition based on genomes includes the Viridiplantae, along with the red algae and the glaucophytes, in the clade Archaeplastida.

There are about 380,000 known species of plants, of which the majority, some 260,000, produce seeds. They range in size from single cells to the tallest trees. Green plants provide a substantial proportion of the world's molecular oxygen; the sugars they create supply the energy for most of Earth's ecosystems; other organisms, including animals, either consume plants directly or rely on organisms which do so.

Grain, fruit, and vegetables are basic human foods and have been domesticated for millennia. People use plants for many purposes, such as building materials, ornaments, writing materials, and, in great variety, for medicines. The scientific study of plants is known as botany, a branch of biology.

Definition

Taxonomic history

All living things were traditionally placed into one of two groups, plants and animals. This classification dates from Aristotle (384–322 BC), who distinguished different levels of beings in his biology, based on whether living things had a "sensitive soul" or like plants only a "vegetative soul". Theophrastus, Aristotle's student, continued his work in plant taxonomy and classification. Much later, Linnaeus (1707–1778) created the basis of the modern system of scientific classification, but retained the animal and plant kingdoms, naming the plant kingdom the Vegetabilia.

Alternative concepts
When the name Plantae or plant is applied to a specific group of organisms or taxa, it usually refers to one of four concepts. From least to most inclusive, these four groupings are:

Evolution

Diversity

There are about 382,000 accepted species of plants, of which the great majority, some 283,000, produce seeds. The table below shows some species count estimates of different green plant (Viridiplantae) divisions. About 85–90% of all plants are flowering plants. Several projects are currently attempting to collect records on all plant species in online databases, e.g. the World Flora Online.

Plants range in scale from single-celled organisms such as desmids (from 10 micrometres across) and picozoa (less than 3 micrometres across), to the largest trees (megaflora) such as the conifer Sequoia sempervirens (up to  tall ) and the angiosperm Eucalyptus regnans (up to  tall ).

The naming of plants is governed by the International Code of Nomenclature for algae, fungi, and plants and the International Code of Nomenclature for Cultivated Plants.

Evolutionary history

The ancestors of land plants evolved in water. An algal scum formed on the land , but it was not until the Ordovician, around , that the first land plants appeared, with a level of organisation like that of bryophytes. However, evidence from carbon isotope ratios in Precambrian rocks suggests that complex plants developed over 1000 mya.

Primitive land plants began to diversify in the late Silurian, around . Bryophytes, club mosses, and ferns then appear in the fossil record. Early plant anatomy is preserved in cellular detail in an early Devonian fossil assemblage from the Rhynie chert. These early plants were preserved by being petrified in chert formed in silica-rich volcanic hot springs.

By the end of the Devonian, most of the basic features of plants today were present, including roots, leaves and secondary wood in trees such as Archaeopteris. The Carboniferous Period saw the development of forests in swampy environments dominated by clubmosses and horsetails, including some as large as trees, and the appearance of early gymnosperms, the first seed plants. The Permo-Triassic extinction event radically changed the structures of communities. This may have set the scene for the evolution of flowering plants in the Triassic (~), with an adaptive radiation in the Cretaceous so rapid that Darwin called it an "abominable mystery". Conifers diversified from the Late Triassic onwards, and became a dominant part of floras in the Jurassic.

Phylogeny

In 2019, a phylogeny based on genomes and transcriptomes from 1,153 plant species was proposed. The placing of algal groups is supported by phylogenies based on genomes from the Mesostigmatophyceae and Chlorokybophyceae that have since been sequenced. Both the "chlorophyte algae" and the "streptophyte algae" are treated as paraphyletic (vertical bars beside phylogenetic tree diagram) in this analysis, as the land plants arose from within those groups. The classification of Bryophyta is supported both by Puttick et al. 2018, and by phylogenies involving the hornwort genomes that have also since been sequenced.

Physiology

Plant cells

Plant cells have distinctive features that other eukaryotic cells (such as those of animals) lack. These include the large water-filled central vacuole, chloroplasts, and the strong flexible cell wall, which is outside the cell membrane. Chloroplasts are derived from what was once a symbiosis of a non-photosynthetic cell and photosynthetic cyanobacteria. The cell wall, made mostly of cellulose, allows plant cells to swell up with water without bursting. The vacuole allows the cell to change in size while the amount of cytoplasm stays the same.

Plant structure

Most plants are multicellular. Plant cells differentiate into multiple cell types, forming tissues such as the vascular tissue with specialized xylem and phloem of leaf veins and stems, and organs with different physiological functions such as roots to absorb water and minerals, stems for support and to transport water and synthesized molecules, leaves for photosynthesis, and flowers for reproduction.

Photosynthesis

Plants photosynthesize, manufacturing food molecules (sugars) using energy obtained from light. Plant cells contain chlorophylls inside their chloroplasts, which are green pigments that are used to capture light energy. The end-to-end chemical equation for photosynthesis is:

6CO2{} + 6H2O{} ->[\text{light}] C6H12O6{} + 6O2{}

This causes plants to release oxygen into the atmosphere. Green plants provide a substantial proportion of the world's molecular oxygen, alongside the contributions from photosynthetic algae and cyanobacteria.

Plants that have secondarily adopted a parasitic lifestyle may lose the genes involved in photosynthesis and the production of chlorophyll.

Growth and repair
Growth is determined by the interaction of a plant's genome with its physical and biotic environment. Factors of the physical or abiotic environment include temperature, water, light, carbon dioxide, and nutrients in the soil. Biotic factors that affect plant growth include crowding, grazing, beneficial symbiotic bacteria and fungi, and attacks by insects or plant diseases.

Frost and dehydration can damage or kill plants. Some plants have antifreeze proteins, heat-shock proteins and sugars in their cytoplasm that enable them to tolerate these stresses. Plants are continuously exposed to a range of physical and biotic stresses which cause DNA damage, but they can tolerate and repair much of this damage.

Reproduction

Plants reproduce to generate offspring, whether sexually, involving gametes, or asexually, involving ordinary growth. Many plants use both mechanisms.

Sexual

When reproducing sexually, plants have complex lifecycles involving alternation of generations. One generation, the sporophyte, which is diploid (with 2 sets of chromosomes), gives rise to the next generation, the gametophyte, which is haploid (with one set of chromosomes). Some plants also reproduce asexually via spores. In some non-flowering plants such as mosses, the sexual gametophyte forms most of the visible plant. In seed plants (gymnosperms and flowering plants), the sporophyte forms most of the visible plant, and the gametophyte is very small. Flowering plants reproduce sexually using flowers, which contain male and female parts: these may be within the same (hermaphrodite) flower, on different flowers on the same plant, or on different plants. The pollen produces male gametes that enter the ovule to fertilize the egg cell of the female gametophyte. Fertilization takes place within the carpels or ovaries, which develop into fruits that contain seeds. Fruits may be dispersed whole, or they may split open and the seeds dispersed individually.

Asexual

Plants reproduce asexually by growing any of a wide variety of structures capable of growing into new plants. At the simplest, plants such as mosses or liverworts may be broken into pieces, each of which may regrow into whole plants. The propagation of flowering plants by cuttings is a similar process. Structures such as runners enable plants to grow to cover an area, forming a clone. Many plants grow food storage structures such as tubers or bulbs which may each develop into a new plant.

Some non-flowering plants, such as many liverworts, mosses and some clubmosses, along with a few flowering plants, grow small clumps of cells called gemmae which can detach and grow.

Disease resistance

Plants use pattern-recognition receptors to recognize pathogens such as bacteria that cause plant diseases. This recognition triggers a protective response. The first such plant receptors were identified in rice and in Arabidopsis thaliana.

Genomics

Plants have some of the largest genomes among all organisms. The largest plant genome (in terms of gene number) is that of wheat (Triticum aestivum), predicted to encode ≈94,000 genes and thus almost 5 times as many as the human genome. The first plant genome sequenced was that of Arabidopsis thaliana which encodes about 25,500 genes. In terms of sheer DNA sequence, the smallest published genome is that of the carnivorous bladderwort (Utricularia gibba) at 82 Mb (although it still encodes 28,500 genes) while the largest, from the Norway spruce (Picea abies), extends over 19.6 Gb (encoding about 28,300 genes).

Ecology

Distribution

Plants are distributed almost worldwide. While they inhabit several biomes which can be divided into a multitude of ecoregions, only the hardy plants of the Antarctic flora, consisting of algae, mosses, liverworts, lichens, and just two flowering plants, have adapted to the prevailing conditions on that southern continent.

Plants are often the dominant physical and structural component of the habitats where they occur. Many of the Earth's biomes are named for the type of vegetation because plants are the dominant organisms in those biomes, such as grassland, savanna, and tropical rainforest.

Primary producers

The photosynthesis conducted by land plants and algae is the ultimate source of energy and organic material in nearly all ecosystems. Photosynthesis, at first by cyanobacteria and later by photosynthetic eukaryotes, radically changed the composition of the early Earth's anoxic atmosphere, which as a result is now 21% oxygen. Animals and most other organisms are aerobic, relying on oxygen; those that do not are confined to relatively rare anaerobic environments. Plants are the primary producers in most terrestrial ecosystems and form the basis of the food web in those ecosystems. Plants form about 80% of the world biomass at about  of carbon.

Ecological relationships

Numerous animals have coevolved with plants; flowering plants have evolved pollination syndromes, suites of flower traits that favour their reproduction. Many, including insect and bird partners, are pollinators, visiting flowers and accidentally transferring pollen in exchange for food in the form of pollen or nectar.

Many animals disperse seeds that are adapted for such dispersal. Various mechanisms of dispersal have evolved. Some fruits offer nutritious outer layers attractive to animals, while the seeds are adapted to survive the passage through the animal's gut; others have hooks that enable them to attach to a mammal's fur.
Myrmecophytes are plants that have coevolved with ants. The plant provides a home, and sometimes food, for the ants. In exchange, the ants defend the plant from herbivores and sometimes competing plants. Ant wastes serve as organic fertilizer.

The majority of plant species have fungi associated with their root systems in a mutualistic symbiosis known as mycorrhiza. The fungi help the plants gain water and mineral nutrients from the soil, while the plant gives the fungi carbohydrates manufactured in photosynthesis.
Some plants serve as homes for endophytic fungi that protect the plant from herbivores by producing toxins. The fungal endophyte Neotyphodium coenophialum in tall fescue grass has pest status in the American cattle industry.

Many legumes have Rhizobium nitrogen-fixing bacteria in nodules of their roots, which fix nitrogen from the air for the plant to use; in return, the plants supply sugars to the bacteria. Nitrogen fixed in this way can become available to other plants, and is important in agriculture; for example, farmers may grow a crop rotation of a legume such as beans, followed by a cereal such as wheat, to provide cash crops with a reduced input of nitrogen fertilizer.

Some 1% of plants are parasitic. They range from the semi-parasitic mistletoe that merely takes some nutrients from its host, but still has photosynthetic leaves, to the fully-parasitic broomrape and toothwort that acquire all their nutrients through connections to the roots of other plants, and so have no chlorophyll. Full parasites can be extremely harmful to their plant hosts.

Plants that grow on other plants, usually trees, without parasitizing them, are called epiphytes. These may support diverse arboreal ecosystems. Some may indirectly harm their host plant, such as by intercepting light. Hemiepiphytes like the strangler fig begin as epiphytes, but eventually set their own roots and overpower and kill their host. Many orchids, bromeliads, ferns, and mosses grow as epiphytes. Among the epiphytes, the bromeliads accumulate water in their leaf axils; these water-filled cavities can support complex aquatic food webs.

Some 630 species of plants are carnivorous, such as the Venus flytrap (Dionaea muscipula) and sundew (Drosera species). They trap small animals and digest them to obtain mineral nutrients, especially nitrogen and phosphorus.

Competition

Competition for shared resources reduces a plant's growth. Shared resources include sunlight, water and nutrients. Light is a critical resource because it is necessary for photosynthesis. Plants use their leaves to shade other plants from sunlight and grow quickly to maximize their own expose. Water too is essential for photosynthesis; roots compete to maximize water uptake from soil. Some plants have deep roots that are able to locate water stored deep underground, and others have shallower roots that are capable of extending longer distances to collect recent rainwater.
Minerals are important for plant growth and development. Common nutrients competed for amongst plants include nitrogen, phosphorus, and potassium.

Importance to humans

Food

Human cultivation of plants is the core of agriculture, which in turn has played a key role in the history of world civilizations. Humans depend on plants for food, either directly or as feed in animal husbandry. Agriculture includes agronomy for arable crops, horticulture for vegetables and fruit, and forestry for timber. About 7,000 species of plant have been used for food, though most of today's food is derived from only 30 species. The major staples include cereals such as rice and wheat, starchy roots and tubers such as cassava and potato, and legumes such as peas and beans. Vegetable oils such as olive oil and palm oil provide lipids, while fruit and vegetables contribute vitamins and minerals to the diet. Coffee, tea, and chocolate are major crops whose caffeine-containing products serve as mild stimulants. The study of plant uses by people is called economic botany or ethnobotany.

Medicines

Medicinal plants are a primary source of organic compounds, both for their medicinal and physiological effects, and for the industrial synthesis of a vast array of organic chemicals. Many hundreds of medicines, as well as narcotics, are derived from plants, both traditional medicines used in herbalism and chemical substances purified from plants or first identified in them, sometimes by ethnobotanical search, and then synthesised for use in modern medicine. Modern medicines derived from plants include aspirin, taxol, morphine, quinine, reserpine, colchicine, digitalis and vincristine. Plants used in herbalism include ginkgo, echinacea, feverfew, and Saint John's wort. The pharmacopoeia of Dioscorides, , describing some 600 medicinal plants, was written between 50 and 70 CE and remained in use in Europe and the Middle East until around 1600 CE; it was the precursor of all modern pharmacopoeias.

Nonfood products

Plants grown as industrial crops are the source of a wide range of products used in manufacturing. Nonfood products include essential oils, natural dyes, pigments, waxes, resins, tannins, alkaloids, amber and cork. Products derived from plants include soaps, shampoos, perfumes, cosmetics, paint, varnish, turpentine, rubber, latex, lubricants, linoleum, plastics, inks, and gums. Renewable fuels from plants include firewood, peat and other biofuels. The fossil fuels coal, petroleum and natural gas are derived from the remains of aquatic organisms including phytoplankton in geological time. Many of the coal fields date to the Carboniferous period of Earth's history. Terrestrial plants also form type III kerogen, a source of natural gas.

Structural resources and fibres from plants are used to construct dwellings and to manufacture clothing. Wood is used for buildings, boats, and furniture, and for smaller items such as musical instruments and sports equipment. Wood is pulped to make paper and cardboard. Cloth is often made from cotton, flax, ramie or synthetic fibres such as rayon, derived from plant cellulose. Thread used to sew cloth likewise comes in large part from cotton.

Ornamental plants

Thousands of plant species are cultivated for their beauty and to provide shade, modify temperatures, reduce wind, abate noise, provide privacy, and reduce soil erosion. Plants are the basis of a multibillion-dollar per year tourism industry, which includes travel to historic gardens, national parks, rainforests, forests with colourful autumn leaves, and festivals such as Japan's and America's cherry blossom festivals.

Plants may be grown indoors as houseplants, or in specialized buildings such as greenhouses. Plants such as Venus flytrap, sensitive plant and resurrection plant are sold as novelties. Art forms specializing in the arrangement of cut or living plant include bonsai, ikebana, and the arrangement of cut or dried flowers. Ornamental plants have sometimes changed the course of history, as in tulipomania.

In science

The traditional study of plants is the science of botany. Basic biological research has often used plants as its model organisms. In genetics, the breeding of pea plants allowed Gregor Mendel to derive the basic laws governing inheritance, and examination of chromosomes in maize allowed Barbara McClintock to demonstrate their connection to inherited traits. The plant Arabidopsis thaliana is used in laboratories as a model organism to understand how genes control the growth and development of plant structures. Tree rings provide a method of dating in archeology, and a record of past climates. The study of plant fossils, or Paleobotany, provides information about the evolutions of plants, paleogeographical reconstructions, and past climate change. Plant fossils can also help determine the age of rocks.

In mythology, religion, and culture

Plants including trees appear in mythology, religion, and literature. In multiple Indo-European, Siberian, and Native American religions, the world tree motif is depicted as a colossal tree growing on the earth, supporting the heavens, and with its roots reaching into the underworld. It may also appear as a cosmic tree or an eagle and serpent tree. Forms of the world tree include the archetypal tree of life, which is in turn connected to the Eurasian concept of the sacred tree. Another widespread ancient motif, found for example in Iran, has a tree of life flanked by a pair of confronted animals.

Flowers are often used as memorials, gifts and to mark special occasions such as births, deaths, weddings and holidays. Flower arrangements may be used to send hidden messages. Plants and especially  flowers form the subjects of many paintings.

Negative effects

Weeds are commercially or aesthetically undesirable plants growing in managed environments such as in agriculture and gardens. People have spread many plants beyond their native ranges; some of these plants have become invasive, damaging existing ecosystems by displacing native species, and sometimes becoming serious weeds of cultivation.

Some plants that produce windblown pollen, including grasses, invoke allergic reactions in people who suffer from hay fever. Many plants produce toxins to protect themselves from herbivores. Major classes of plant toxins include alkaloids, terpenoids, and phenolics. These can be harmful to humans and livestock by ingestion or, as with poison ivy, by contact. Some plants have negative effects on other plants, preventing seedling growth or the growth of nearby plants by releasing allopathic chemicals.

See also

 Plant identification

References

Further reading
General:
 Evans, L.T. (1998). Feeding the Ten Billion – Plants and Population Growth. Cambridge University Press. Paperback, 247 pages. .
 Kenrick, Paul & Crane, Peter R. (1997). The Origin and Early Diversification of Land Plants: A Cladistic Study. Washington, D.C.: Smithsonian Institution Press. .
 Raven, Peter H.; Evert, Ray F.; & Eichhorn, Susan E. (2005). Biology of Plants (7th ed.). New York: W.H. Freeman and Company. .
 Taylor, Thomas N. & Taylor, Edith L. (1993). The Biology and Evolution of Fossil Plants. Englewood Cliffs, NJ: Prentice Hall. .

Species estimates and counts:
 International Union for Conservation of Nature and Natural Resources (IUCN) Species Survival Commission (2004). IUCN Red List The IUCN Red List of Threatened Species.

External links

 Index Nominum Algarum
 Interactive Cronquist classification. Archived 10 February 2006.
 Plant Resources of Tropical Africa. Archived 11 June 2010.
 Tree of Life. .

Botanical and vegetation databases
 African Plants Initiative database
 Australia
 Chilean plants at Chilebosque
 e-Floras (Flora of China, Flora of North America and others). .
 Flora Europaea
 Flora of Central Europe
 Flora of North America. .
 List of Japanese Wild Plants Online. .
 Meet the Plants-National Tropical Botanical Garden. Archived 16 June 2007.
 Lady Bird Johnson Wildflower Center – Native Plant Information Network at University of Texas, Austin
 United States Department of Agriculture not limited to continental US species.

Plants

Plant