Elms are deciduous and semi-deciduous trees comprising the flowering plant genus Ulmus in the plant family Ulmaceae. The genus first appeared in the Miocene geological period about 20 million years ago, originating in what is now central Asia; these trees flourished and spread over most of the Northern Hemisphere, inhabiting the temperate and tropical-montane regions of North America and Eurasia, presently ranging southward across the Equator into Indonesia. Elms are components of many kinds of natural forests. Moreover, during the 19th and early 20th centuries many species and cultivars were planted as ornamental street and park trees in Europe, North America, parts of the Southern Hemisphere, notably Australasia; some individual elms reached great age. However, in recent decades, most mature elms of European or North American origin have died from Dutch elm disease, caused by a microfungus dispersed by bark beetles. In response, disease-resistant cultivars have been developed, capable of restoring the elm to forestry and landscaping.
There are about 30 to 40 species of Ulmus. Oliver Rackham describes Ulmus as the most critical genus in the entire British flora, adding that'species and varieties are a distinction in the human mind rather than a measured degree of genetic variation'. Eight species are endemic to North America, a smaller number to Europe; the classification adopted in the List of elm species, varieties and hybrids is based on that established by Brummitt. A large number of synonyms have accumulated over the last three centuries. Botanists who study elms and argue over elm identification and classification are called pteleologists, from the Greek πτελέα; as part of the sub-order urticalean rosids they are distant cousins of cannabis and nettles. The name Ulmus is the Latin name for these trees, while the English "elm" and many other European names are either cognate with or derived from it; the genus is hermaphroditic, having apetalous perfect flowers. Elm leaves are alternate, with simple, single- or, most doubly serrate margins asymmetric at the base and acuminate at the apex.
The fruit is a round wind-dispersed samara flushed with chlorophyll, facilitating photosynthesis before the leaves emerge. The samarae are light, those of British elms numbering around 50,000 to the pound. All species are tolerant of a wide range of soils and pH levels but, with few exceptions, demand good drainage; the elm tree can grow to great height with a forked trunk creating a vase profile. Dutch elm disease devastated elms throughout Europe and much of North America in the second half of the 20th century, it derives its name'Dutch' from the first description of the disease and its cause in the 1920s by the Dutch botanists Bea Schwarz and Christina Johanna Buisman. Owing to its geographical isolation and effective quarantine enforcement, Australia has so far remained unaffected by Dutch Elm Disease, as have the provinces of Alberta and British Columbia in western Canada. DED is caused by a micro-fungus transmitted by two species of Scolytus elm-bark beetle which act as vectors; the disease affects all species of elm native to North America and Europe, but many Asiatic species have evolved anti-fungal genes and are resistant.
Fungal spores, introduced into wounds in the tree caused by the beetles, invade the xylem or vascular system. The tree responds by producing tyloses blocking the flow from roots to leaves. Woodland trees in North America are not quite as susceptible to the disease because they lack the root-grafting of the urban elms and are somewhat more isolated from each other. In France, inoculation with the fungus of over three hundred clones of the European species failed to find a single variety possessed of any significant resistance; the first, less aggressive strain of the disease fungus, Ophiostoma ulmi, arrived in Europe from the Far East in 1910, was accidentally introduced to North America in 1928, but was weakened by viruses and had all but disappeared in Europe by the 1940s. The second, far more virulent strain of the disease Ophiostoma novo-ulmi was identified in Europe in the late 1960s, within a decade had killed over 20 million trees in the UK alone. Three times more deadly, the new strain arrived in Europe from the US on a cargo of Rock Elm.
There is no sign of the current pandemic waning, no evidence of a susceptibility of the fungus to a disease of its own caused by d-factors: occurring virus-like agents that debilitated the original O. ulmi and reduced its sporulation. Elm phloem necrosis is a disease of elm trees, spread by leafhoppers or by root grafts; this aggressive disease, with no known cure, occurs in the Eastern United States, southern Ontario in Canada, Europe. It is caused by phytoplasmas. Infection and death of the phloem girdles the tree and stops the flow of water and nutrients; the disease affects cultivated trees. Cutting the infected tree before the disease establishes itself and cleanup and prompt disposal of infected matter has resul
Brest Brest-Litowsk, is a city in Belarus at the border with Poland opposite the Polish city of Terespol, where the Bug and Mukhavets rivers meet. It is the capital city of the Brest Region; the city of Brest is a historic site of many cultures. It was the location of important historical events such as the Union of Brest and Treaty of Brest-Litovsk; the Brest Fortress was recognized by the Soviet Union as the Hero Fortress in honor of the defense of Brest Fortress in June 1941. During medieval times, the city was part of the Kingdom of Poland from 1020 until 1319 when it was taken by the Grand Duchy of Lithuania, it became part of the Polish–Lithuanian Commonwealth in 1569. As a result of the Partitions of Poland, it was incorporated into the Russian Empire in 1795. After World War I, the city returned to Second Polish Republic. During the Invasion of Poland by Nazi Germany and the Soviet Union in 1939 the city was first captured by the Wehrmacht and soon passed on to the USSR in accordance with German–Soviet Frontier Treaty.
In 1941 it was taken again by the Nazis during Operation Barbarossa. After the war, once the new boundaries between the USSR and Poland were ratified, the city became part of the Belarusian SSR and as such was part of the Soviet Union until the breakup of the USSR in 1991. Brest is now a part of an independent Belarus. Several theories attempt to explain the origin of the city's name, it may have come from the Slavic root beresta meaning "birch", or "bark". The name could originate from the Slavic root berest meaning "elm". Or it could have come from the Lithuanian word brasta meaning "ford". Once a center of Jewish scholarship, the city has the Yiddish name בריסק, hence the term "Brisker" used to describe followers of the influential Soloveitchik family of rabbis. Traditionally, Belarusian-speakers called the city Берасце. Brest became part of the Grand Duchy of Lithuania in 1319. In the Polish–Lithuanian Commonwealth formed in 1569 the town became known in Polish as Brześć Brześć Litewski. Brześć became part of the Russian Empire under the name Brest-Litovsk or Brest-Litovskii in the course of the Third Partition of the Polish-Lithuanian Commonwealth in 1795.
After World War I, the rebirth of Poland in 1918, the government of the Second Polish Republic renamed the city as Brześć nad Bugiem on March 20, 1923. After World War II the city became part of the Byelorussian Soviet Socialist Republic with the name simplified as Brest. Brest's coat of arms, adopted on January 26, 1991, features an arrow pointed upwards and a bow on a sky-blue shield. An alternative coat of arms has a red shield. Sigismund II Augustus, King of Poland and Grand Duke of Lithuania, first granted Brest a coat of arms in 1554; the city was founded by the Slavs. As a town, Brest – Berestye in Kievan Rus – was first mentioned in the Primary Chronicle in 1019 when the Kievan Rus took the stronghold from the Poles, it is one of the oldest cities in Belarus. It was hotly contested between the Polish rulers and Kievan Rus princes, laid waste by the Mongols in 1241, was not rebuilt until 1275, it was part of the territory of the Grand Duchy of Lithuania. In 1390 Brest became the first city in the lands that now comprise Belarus to receive Magdeburg rights.
Its suburbs were burned by the Teutonic Knights in 1379. In 1409 it was a meeting place of King Władysław II Jagiełło, duke Vytautas and Tatar khan under the archbishop Mikołaj Trąba initiative, to prepare for war with the Teutonic Knights. In 1410 the town mustered a cavalry company that participated in the Polish-Lithuanian victory at the battle of Grunwald. In 1419 it become a seat of the starost in the newly created Trakai Voivodeship. In 1500 it was burned again by Crimean Tatars. In 1566, following king Sigismund II Augustus decree, a new voivodeship was created - Brest Litovsk Voivodeship. After it became part of the Polish–Lithuanian Commonwealth in 1569, it was renamed Brest-Litovsk. During the period of the union of the Polish–Lithuanian Commonwealth and Sweden under king Sigismund III Vasa, diets were held there. In 1594 and 1596 it was the meeting-place of two remarkable councils of regional bishops of the Roman-Catholic Church and Eastern Orthodox Church; the 1596 council established the Uniate Church.
In 1657, again in 1706, the town and castle were captured by the Swedes during their invasions of the Polish-Lithuanian Commonwealth. In an attack from the other direction, on January 13, 1660 the invading Muscovite Russian army under Ivan Andreyevich Khovansky took the Brest Castle in a surprise early morning attack, the town having been captured earlier, massacred the 1,700 defenders and their families. On July 23, 1792 a battle was fought between the regiments of the Duchy of Lithuania defending the town and the invading Russian Imperial Army. On September 19, 1794 the area between Brest and Terespol was the scene of a victorious battle won by the invading Russian Imperial army under Suvorov over the Kościuszko Uprising army division under general Karol Sierakowski (known in Russian sourc
The genus Tamarix is composed of about 50–60 species of flowering plants in the family Tamaricaceae, native to drier areas of Eurasia and Africa. The generic name may refer to the Tamaris River in Hispania Tarraconensis, they are evergreen or deciduous shrubs or trees growing to 1–18 m in height and forming dense thickets. The largest, Tamarix aphylla, is an evergreen tree, they grow on saline soils, tolerating up to 15,000 ppm soluble salt and can tolerate alkaline conditions. Tamarisks are characterized by grey-green foliage; the bark of young branches is reddish brown. As the plants age, the bark becomes bluish-purple and furrowed; the leaves are scale-like like that of junipers, 1–2 mm long, overlap each other along the stem. They are encrusted with salt secretions; the pink to white flowers appear in dense masses on 5–10 cm long spikes at branch tips from March to September, though some species tend to flower during the winter. Tamarix can spread both vegetatively, by adventitious roots or submerged stems, sexually, by seeds.
Each flower can produce thousands of tiny seeds that are contained in a small capsule adorned with a tuft of hair that aids in wind dispersal. Seeds can be dispersed by water. Seedlings require extended periods of soil saturation for establishment. Tamarisk trees are most propagated by cuttings. Tamarix species are fire-adapted, have long tap roots that allow them to intercept deep water tables and exploit natural water resources, they are able to limit competition from other plants by taking up salt from deep ground water, accumulating it in their foliage, from there depositing it in the surface soil where it builds up concentrations temporarily detrimental to some plants. The salt is washed away during heavy rains. Tamarix species are used as food plants by the larvae of some Lepidoptera species including Coleophora asthenella which feeds on T. africana. Tamarisk species are used as ornamental shrubs and shade trees: notably T. ramosissima and T. tetrandraThis wood was used by the Saka to produce tremendously powerful bows hundreds of years before the common era.
The wood may be used for carpentry or firewood: it is a possible agroforestry species Plans are being made for the tamarisk to play a role in antidesertification programs in China Salt cedars can be planted to mine salts be used in the production of fuel and fertilizer Tamarix ramosissima has naturalized and become a major invasive plant species in parts of the world, such as in the Southwestern United States and Desert Region of California, consuming large amounts of groundwater in riparian and oasis habitats due to the density of its stands. The high salt level in tamarisk infiltrates the soil preventing other plants from growing, creating a tamarisk dominant forest with no understory, void of important habitat for pollinators and other native species. Tamarisk forests tend to burn hotter than most native riparian trees, acres of uninterrupted tamarisk is a fire hazard and a risk to human structures. Tamarisk eradication projects use a combination of methods, including manual stem cutting followed by application of herbicide to the stump and burning.
Myricaria germanica Desv. The tamarisk was introduced to the United States as an ornamental shrub, a windbreak, a shade tree in the early 19th century. In the 1930s, during the Great Depression, tree-planting was used as a tool to fight soil erosion on the Great Plains, the trees were planted by the millions in the Great Plains Shelterbelt. Eight species are found in North America, they can be divided into two subgroups: Evergreen speciesTamarix aphylla, a large evergreen tree, does not sexually reproduce in the local climate and is not considered a invasive species. The Athel tree is used for windbreaks on the edge of agricultural fields and as a shade tree in the deserts of the Southwestern United States. Deciduous speciesThe second subgroup contains the deciduous tamarisks, which are small, shrubby trees known as "saltcedars"; these include Tamarix pentandra, Tamarix tetranda, Tamarix gallica, Tamarix chinensis, Tamarix ramosissima, Tamarix parvifolia. These deciduous trees establish themselves in disturbed and undisturbed streams, bottom lands and drainage washes of natural or artificial water bodies, moist rangelands and pastures, other areas where seedlings can be exposed to extended periods of saturated soil for establishment.
Tamarix species are believed to disrupt the structure and stability of North American native plant communities and degrade native wildlife habitat, by outcompeting and replacing native plant species, salinizing soils, monopolizing limited sources of moisture, increasing the frequency and effect of fires and floods. While individual plants may not consume larger quantities of water than native species, dense stands of tamarisk do consume more water than equivalent stands of native cottonwoods. An active and ongoing debate exists as to when the tamarisk can out-compete native plants, if it is displacing native plants or it just taking advantage of disturbance by removal of natives by humans and changes in flood regimens. Research on competition between tamarisk seedlings and co-occurring native trees has found that the seedlings are not competitive over a range of environments, but stands of mature trees prevent native species' establishment in the understory, due to low light, elevated salinity, possibly
Europe is a continent located in the Northern Hemisphere and in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west and the Mediterranean Sea to the south, it comprises the westernmost part of Eurasia. Since around 1850, Europe is most considered to be separated from Asia by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas and the waterways of the Turkish Straits. Although the term "continent" implies physical geography, the land border is somewhat arbitrary and has been redefined several times since its first conception in classical antiquity; the division of Eurasia into two continents reflects East-West cultural and ethnic differences which vary on a spectrum rather than with a sharp dividing line. The geographic border does not follow political boundaries, with Turkey and Kazakhstan being transcontinental countries. A strict application of the Caucasus Mountains boundary places two comparatively small countries and Georgia, in both continents.
Europe covers 2 % of the Earth's surface. Politically, Europe is divided into about fifty sovereign states of which the Russian Federation is the largest and most populous, spanning 39% of the continent and comprising 15% of its population. Europe had a total population of about 741 million as of 2016; the European climate is affected by warm Atlantic currents that temper winters and summers on much of the continent at latitudes along which the climate in Asia and North America is severe. Further from the sea, seasonal differences are more noticeable than close to the coast. Europe, in particular ancient Greece, was the birthplace of Western civilization; the fall of the Western Roman Empire in 476 AD and the subsequent Migration Period marked the end of ancient history and the beginning of the Middle Ages. Renaissance humanism, exploration and science led to the modern era. Since the Age of Discovery started by Portugal and Spain, Europe played a predominant role in global affairs. Between the 16th and 20th centuries, European powers controlled at various times the Americas all of Africa and Oceania and the majority of Asia.
The Age of Enlightenment, the subsequent French Revolution and the Napoleonic Wars shaped the continent culturally and economically from the end of the 17th century until the first half of the 19th century. The Industrial Revolution, which began in Great Britain at the end of the 18th century, gave rise to radical economic and social change in Western Europe and the wider world. Both world wars took place for the most part in Europe, contributing to a decline in Western European dominance in world affairs by the mid-20th century as the Soviet Union and the United States took prominence. During the Cold War, Europe was divided along the Iron Curtain between NATO in the West and the Warsaw Pact in the East, until the revolutions of 1989 and fall of the Berlin Wall. In 1949 the Council of Europe was founded, following a speech by Sir Winston Churchill, with the idea of unifying Europe to achieve common goals, it includes all European states except for Belarus and Vatican City. Further European integration by some states led to the formation of the European Union, a separate political entity that lies between a confederation and a federation.
The EU originated in Western Europe but has been expanding eastward since the fall of the Soviet Union in 1991. The currency of most countries of the European Union, the euro, is the most used among Europeans. In classical Greek mythology, Europa was a Phoenician princess; the word Europe is derived from her name. The name contains the elements εὐρύς, "wide, broad" and ὤψ "eye, countenance", hence their composite Eurṓpē would mean "wide-gazing" or "broad of aspect". Broad has been an epithet of Earth herself in the reconstructed Proto-Indo-European religion and the poetry devoted to it. There have been attempts to connect Eurṓpē to a Semitic term for "west", this being either Akkadian erebu meaning "to go down, set" or Phoenician'ereb "evening, west", at the origin of Arabic Maghreb and Hebrew ma'arav. Michael A. Barry, professor in Princeton University's Near Eastern Studies Department, finds the mention of the word Ereb on an Assyrian stele with the meaning of "night, sunset", in opposition to Asu " sunrise", i.e. Asia.
The same naming motive according to "cartographic convention" appears in Greek Ἀνατολή. Martin Litchfield West stated that "phonologically, the match between Europa's name and any form of the Semitic word is poor." Next to these hypotheses there is a Proto-Indo-European root *h1regʷos, meaning "darkness", which produced Greek Erebus. Most major world languages use words derived from Europa to refer to the continent. Chinese, for example, uses the word Ōuzhōu. In some Turkic languages the Persian name Frangistan is used casually in referring to much of Europe, besides official names such as Avrupa or Evropa; the prevalent definition of Europe as a geographical term has been in use since the mid-19th century. Europe is taken to be bounded by large bodies of water
A spruce is a tree of the genus Picea, a genus of about 35 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal regions of the Earth. Spruces are large trees, from about 20–60 m tall when mature, have whorled branches and conical form, they can be distinguished from other members of the pine family by their needles, which are four-sided and attached singly to small persistent peg-like structures on the branches, by their cones, which hang downwards after they are pollinated. The needles are shed. In other similar genera, the branches are smooth. Spruce are used as food plants by the larvae of some Lepidoptera species, such as the eastern spruce budworm, they are used by the larvae of gall adelgids. In the mountains of western Sweden, scientists have found a Norway spruce, nicknamed Old Tjikko, which by reproducing through layering, has reached an age of 9,550 years and is claimed to be the world's oldest known living tree; the word spruce comes from a Middle English adjective spruse which meant from Prussia.
The adjective comes from an unknown alteration of an Old French form of Prussia - Pruce, which itself comes from New Latin, which adapted it from Old Prussian. Spruce and Sprws seem to have been generic terms for commodities brought to England by Hanseatic merchants, the tree thus was believed to be particular to Prussia, which for a time was figurative in England as a land of luxuries. DNA analyses have shown that traditional classifications based on the morphology of needle and cone are artificial. A recent study found that P. breweriana had a basal position, followed by P. sitchensis, the other species were further divided into three clades, suggesting that Picea originated in North America. Spruce has been found in the fossil record from the early Cretaceous, 136 million years ago. Thirty-five named species of spruce exist in the world; the Plant List has 59 accepted spruce names. Basal species: Picea breweriana – Brewer's spruce, Klamath Mountains, North America. Beyond that, determination can become more difficult.
Intensive sampling in the Smithers/Hazelton/Houston area of British Columbia showed Douglas, according to Coates et al. that cone scale morphology was the feature most useful in differentiating species of spruce. Daubenmire, after range-wide sampling, had recognized the importance of the 2 latter characters. Taylor had noted that the most obvious morphological difference
Liepāja is a city in western Latvia, located on the Baltic Sea. It is the largest city in the Kurzeme Region and the third largest city in the country after Riga and Daugavpils, it is an important ice-free port. In 2017 population of Liepāja is 69,443 people. In the 19th and early 20th century it was a favourite place for sea-bathers with the town boasting a fine park and many pretty gardens, a theatre. Liepāja is however known throughout Latvia as "City where the wind is born" because of the constant sea breeze. A song of the same name has become the anthem of the city, its reputation as the windiest city in Latvia was strengthened with the construction of the largest wind farm in the nation nearby. The coat of arms of Liepāja was adopted four days after the jurisdiction gained city rights on 18 March 1625; these are described as: "on a silver background, the lion of Courland with a divided tail, who leans upon a linden tree with its forelegs". The flag of Liepāja has the coat of arms in the center, with red in the top half and green in the bottom.
It is said that the first settlement at the location of modern Liepāja was known by the name Līva from the name of the river Līva on which Liepāja was located. The name was derived from the Livonian word Liiv meaning "sand"; the oldest written text mentioning Līva village is the treaty of bishop of Courland and the master of the Livonian Order dated 4 April 1253. In 1263, the Teutonic Order established a town; the Latvian name Liepāja was mentioned for the first time in 1649 by Paul Einhorn in his work Historia Lettica. A Russian name from the time of the Russian Empire was Либава or Либау, although Лиепая, a transliteration of Liepāja has been used since World War II; some other names for the city include Liepoja in Lithuanian, Lipawa in Polish and ליבאַװע in Yiddish. It is said that the original settlement at the location of modern Liepāja was founded by Curonian fishermen from Piemare as Līva, but Henry of Livonia, in his famous Chronicle, makes no mention of the settlement; the Teutonic Order established a town which they called Libau here in 1263, followed by Mitau two years later.
In 1418 the village was burned by the Lithuanians. During the 15th century, a part of the trade route from Amsterdam to Moscow passed through Līva, where it was known as the "white road to Lyva portus". By 1520 the river Līva had become too shallow for easy navigation, development of the city declined. In 1560, Gotthard Kettler loaned all the Grobiņa district, including Libau, to Albert, Duke of Prussia for 50,000 guldens. Only in 1609 after the marriage of Sofie Hohenzollern, Princess of Prussia, to Wilhelm Kettler did the territory return to the Duchy. During the Livonian War, Libau was burnt by the Swedes. In 1625, Duke Friedrich Kettler of Courland granted the town city rights, which were affirmed by King Sigismund III of Poland in 1626, although under what legal authority Sigismund had is debatable. Under Duke Jacob Kettler, Libau became one of the main ports of Courland as it reached the height of its prosperity. In 1637 Couronian colonization was started from the ports of Ventspils. Kettler was an eager proponent of mercantilist ideas.
Metalworking and ship building became much more developed, trading relations developed not only with nearby countries, but with Britain, the Netherlands and Portugal. In 1697–1703 a canal was cut to the sea and a more modern port was built. In 1701, during the Great Northern War, Libau was captured by Charles XII of Sweden, but by the end of the war, the city had returned to titular Polish possession. In 1710 an epidemic of plague killed about a third of the population. In 1780 the first Freemasonry lodge, "Libanons," was established by Provincial Grand Master Ivan Yelagin on behalf of the Provincial Lodge of Russia. Courland passed to the control of the Russian Empire in 1795 during the third Partition of Poland and was organized as the Courland Governorate of Russia. Growth during the nineteenth century was rapid. During the Crimean War, when the British Royal Navy was blockading Russian Baltic ports, the busy yet still unfortified port of Libau was captured on 17 May 1854 without a shot being fired, by a landing party of 110 men from HMS Conflict and HMS Amphion.
In 1857 an Imperial Decree provided for a new railway to Libau, the same year the engineer Jan Heidatel developed a project to reconstruct the port. In 1861–1868 the project was realized – including the building of a lighthouse and breakwaters. Between 1877–1882 the political and literary weekly newspaper Liepājas Pastnieks was published – the first Latvian language newspaper in Libau. In the 1870s the further rapid development of Russian railways the 1871 opening of the Libava-Kaunas and the 1876 Liepāja–Romny Railways, ensured that a large proportion of central Russian trade passed through Libau. By 1900, 7% of Russian exports were passing through Libau; the city became a major port of the Russian Empire on the Baltic Sea, as well as a popular resort. On the orders of Alexander III, Libau was fortified against possible German attacks. Fortifications were subsequently built around the city, in the early 20th century, a major military base was established on the northern edge, it included extensive quarters for military personnel.
As part of the military development, a separate port was excavated for military use. This area became known as Kara Osta and served military needs through
Platanus is a genus consisting of a small number of tree species native to the Northern Hemisphere. They are the sole living members of the family Platanaceae. All members of Platanus are tall. All except for P. kerrii are deciduous, most are found in riparian or other wetland habitats in the wild, though proving drought-tolerant in cultivation. The hybrid London plane has proved tolerant of urban conditions, has been planted in London and elsewhere in the United Kingdom, they are known in English as planes or plane trees. Some North American species are called sycamores, although the term sycamore refers to the fig Ficus sycomorus, the plant so named, to the sycamore maple Acer pseudoplatanus; the genus name Platanus comes from Ancient Greek πλάτανος. The flowers are borne in balls. Male and female flowers are separate, but borne on the same plant; the number of heads in one cluster is indicative of the species. The male flower has 3–8 stamens. Plane trees are wind-pollinated. Male flower-heads fall off after shedding their pollen.
After being pollinated, the female flowers become achenes. The fruit is a multiple of achenes; the core of the ball is 1 cm in diameter and is covered with a net of mesh 1 mm, which can be peeled off. The ball is 2.5–4 cm in diameter and contains several hundred achenes, each of which has a single seed and is conical, with the point attached downward to the net at the surface of the ball. There is a tuft of many thin stiff yellow-green bristle fibers attached to the base of each achene; these bristles help in wind dispersion of the fruits as in the dandelion. The leaves are alternate. In the subgenus Platanus they have a palmate outline; the base of the leaf stalk is enlarged and wraps around the young stem bud in its axil. The axillary bud is exposed; the mature bark peels off or exfoliates in irregularly shaped patches, producing a mottled, scaly appearance. On old trunks, bark may not thickens and cracks instead. There are two subgenera, subgenus Castaneophyllum containing the anomalous P. kerrii, subgenus Platanus, with all the others.
Within subgenus Platanus, genetic evidence suggests that P. racemosa is more related to P. orientalis than it is to the other North American species. There are fossil records of plane trees as early as 115 million years. Despite the geographic separation between North America and Old World, species from these continents will cross resulting in fertile hybrids such as the London plane; the following are recognized species of plane trees: Planes are susceptible to plane anthracnose, a fungal disease that can defoliate the trees in some years. The most severe infections are associated with wet spring weather. P. occidentalis and the other American species are the most susceptible, with P. orientalis the most resistant. The hybrid London plane is intermediate in resistance. Ceratocystis platani, a wilt disease, has become a significant problem in recent years in much of Europe; the North American species are resistant to the disease, with which they coevolved, while the old world species are sensitive.
Other diseases such as powdery mildew occur but are of lesser importance. Platanus species are used as food plants by the larvae of some Lepidoptera species including Phyllonorycter platani and Setaceous Hebrew Character. In the 21st century a disease known as Massaria disease, has attacked plane trees across Europe, it is caused by the fungus Splanchnonema platani, causes large lesions on the upper sides of branches. The principal use of these trees is as ornamental trees in urban areas and by roadsides; the London plane is popular for this purpose. The American plane is cultivated sometimes for timber and investigations have been made into its use as a biomass crop; the oriental plane is used as an ornamental and has a number of minor medicinal uses. Most significant aspects of cultural history apply to Platanus orientalis in the Old World; the tree is an important part of the literary scenery of Plato's dialogue Phaedrus. Because of Plato, the tree played an important role in the scenery of Cicero's De Oratore.
The legendary Dry tree first recorded by Marco Polo was a platanus. According to the legend, it marked the site of the battle between Alexander the Great and Darius III; the German camouflage pattern Platanenmuster, designed in 1937–1942 by Johann Georg Otto Schick, was the first dotted camouflage pattern. BooksNaumann, Helmut. "Die Platane von Gortyna". In Kämmerer. Thomas Richard. Studien zu Ritual und Sozialgeschichte im Alten. Berlin, de Gruyter. Pp. 207–226. Sunset Western Garden Book. 1995. Pp. 606–607. JournalsFeng, Y.. H.. S.. "Phylogeny and Historical Biogeography of the Genus Platanus as Inferred From Nuclear and Chloroplast DNA". Systematic Botany. 30: 786–799. Doi:10.1600/036364405775097851. Nixon, K. C.. "Revision of the Mexican and Guatemalan species of Platanus". Lundellia. 6: 103–137. Doi:10.2