Populus is a genus of 25–35 species of deciduous flowering plants in the family Salicaceae, native to most of the Northern Hemisphere. English names variously applied to different species include poplar /ˈpɒp.lər/, aspen, and cottonwood.
In the September 2006 issue of Science Magazine, the Joint Genome Institute announced that the western balsam poplar (P. trichocarpa) was the first tree whose full DNA code had been determined by DNA sequencing.
|Leaf of Populus tremula|
|Sections and Species|
The genus has a large genetic diversity, and can grow from 15–50 m (49–164 ft) tall, with trunks up to 2.5 m (8 ft 2 in) in diameter.
The bark on young trees is smooth, white to greenish or dark grey, and often has conspicuous lenticels; on old trees, it remains smooth in some species, but becomes rough and deeply fissured in others. The shoots are stout, with (unlike in the related willows) the terminal bud present. The leaves are spirally arranged, and vary in shape from triangular to circular or (rarely) lobed, and with a long petiole; in species in the sections Populus and Aigeiros, the petioles are laterally flattened, so that breezes easily cause the leaves to wobble back and forth, giving the whole tree a "twinkling" appearance in a breeze. Leaf size is very variable even on a single tree, typically with small leaves on side shoots, and very large leaves on strong-growing lead shoots. The leaves often turn bright gold to yellow before they fall during autumn.
The flowers are mostly dioecious (rarely monoecious) and appear in early spring before the leaves. They are borne in long, drooping, sessile or pedunculate catkins produced from buds formed in the axils of the leaves of the previous year. The flowers are each seated in a cup-shaped disk which is borne on the base of a scale which is itself attached to the rachis of the catkin. The scales are obovate, lobed, and fringed, membranous, hairy or smooth, and usually caducous. The male flowers are without calyx or corolla, and comprise a group of four to 60 stamens inserted on a disk; filaments are short and pale yellow; anthers are oblong, purple or red, introrse, and two-celled; the cells open longitudinally. The female flower also has no calyx or corolla, and comprises a single-celled ovary seated in a cup-shaped disk. The style is short, with two to four stigmata, variously lobed, and numerous ovules. Pollination is by wind, with the female catkins lengthening considerably between pollination and maturity. The fruit is a two- to four-valved dehiscent capsule, green to reddish-brown, mature in midsummer, containing numerous minute light brown seeds surrounded by tufts of long, soft, white hairs which aid wind dispersal.
Poplars and aspens are important food plants for the larvae of a large number of Lepidoptera species. Pleurotus populinus, the aspen oyster mushroom, is found exclusively on dead wood of Populus trees in North America.
Several species of Populus in the United Kingdom and other parts of Europe have experienced heavy dieback; this is thought in part to be due to Sesia apiformis which bores into the trunk of the tree during its larval stage.
The genus Populus has traditionally been divided into six sections on the basis of leaf and flower characters; this classification is followed below. Recent genetic studies have largely supported this, confirming some previously suspected reticulate evolution due to past hybridisation and introgression events between the groups. Some species (noted below) had differing relationships indicated by their nuclear DNA (paternally inherited) and chloroplast DNA sequences (maternally inherited), a clear indication of likely hybrid origin. Hybridisation continues to be common in the genus, with several hybrids between species in different sections known.
Many poplars are grown as ornamental trees, with numerous cultivars used. They have the advantage of growing to a very large size at a rapid pace. Almost all poplars take root readily from cuttings or where broken branches lie on the ground (they also often have remarkable suckering abilities, and can form huge colonies from a single original tree, such as the famous Pando forest made of thousands of Populus tremuloides clones).
Trees with fastigiate (erect, columnar) branching are particularly popular, and are widely grown across Europe and southwest Asia. However, like willows, poplars have very vigorous and invasive root systems stretching up to 40 m from the trees; planting close to houses or ceramic water pipes may result in damaged foundations and cracked walls and pipes due to their search for moisture.
A simple, reproducible, high-frequency micropropagation protocol in eastern cottonwood Populus deltoides has been reported by Yadav et al. 2009.
In India, the poplar is grown commercially by farmers, mainly in the Punjab region. Common poplar varieties are:
The trees are grown from kalam or cuttings, harvested annually in January and February, and commercially available up to 15 November.
Most commonly used to make plywood, Yamuna Nagar in Haryana state has a large plywood industry reliant upon poplar. It is graded according to sizes known as "over" (over 24 inches (610 mm)), "under" (18–24 inches (460–610 mm)), and "sokta" (less than 18 inches (460 mm)).
Although the wood from Populus is known as poplar wood, a common high-quality hardwood "poplar" with a greenish colour is actually from an unrelated genus Liriodendron. Populus wood is a lighter, more porous material.
Its flexibility and close grain make it suitable for a number of applications, similar to those for willow. The Greeks and Etruscans made shields of poplar, and Pliny also recommended poplar for this purpose. Poplar continued to be used for shield construction through the Middle Ages and was renowned for a durability similar to that of oak, but at a substantial reduction in weight.
Interest exists in using poplar as an energy crop for biomass, in energy forestry systems, particularly in light of its high energy-in to energy-out ratio, large carbon mitigation potential, and fast growth.
In the United Kingdom, poplar (as with fellow energy crop willow) is typically grown in a short rotation coppice system for two to five years (with single or multiple stems), then harvested and burned - the yield of some varieties can be as high as 12 oven-dry tonnes per hectare every year. In warmer regions like Italy this crop can procuce up to 13.8, 16.4 oven-dry tonnes of biomass per hectare every year for biannual and triennial cutting cycles also showing a positive energy balance and a high energy efficiency.
Biofuel is another option for using poplar as bioenergy supply. In the United States, scientists studied converting short rotation coppice poplar into sugars for biofuel (e.g. ethanol) production. Considering the relative cheap price, the process of making biofuel from SRC can be economic feasible, although the conversion yield from short rotation coppice (as juvenile crops) were lower than regular mature wood. Besides biochemical conversion, thermochemical conversion (e.g. fast pyrolysis) was also studied for making biofuel from short rotation coppice poplar and was found to have higher energy recovery than that from bioconversion.
Poplar was the most common wood used in Italy for panel paintings; the Mona Lisa and most famous early renaissance Italian paintings are on poplar. The wood is generally white, often with a slightly yellowish colour.
Some stringed instruments are made with one-piece poplar backs; violas made in this fashion are said to have a particularly resonant tone. Similarly, though typically it is considered to have a less attractive grain than the traditional sitka spruce, poplar is beginning to be targeted by some harp luthiers as a sustainable and even superior alternative for their sound boards: in these cases another hardwood veneer is sometimes applied to the resonant poplar base both for cosmetic reasons, and supposedly to fine-tune the acoustic properties.
Poplars in Ukrainian folklore symbolise beauty or loneliness of a woman in love.
The Odd Poplars Alley, in Iași, Romania, is one of the spots where Mihai Eminescu sought inspiration in his works (the poem "Down Where the Lonely Poplars Grow"). In 1973, the 15 white poplars still left (with age ranges between 233 and 371 years) were declared natural monuments.
In Pakistan, poplar is grown on commercial level by farmers in Punjab, Sindh, and Khyber Pakhtunkhwa Provinces. However, all varieties are seriously susceptible to termite attack, causing significant losses to poplar every year. Logs of poplar are therefore also used as bait in termite traps (termaps) for biocontrol of termites in crops.
Poplar represents a suitable candidate for phytoremediation. This plant has been successfully used to target many types of pollutants including trace element (TEs) in soil  and sewage sludge, Polychlorinated Biphenyl (PCBs), Trichloroethylene (TCE), Polycyclic Aromatic Hydrocarbon (PAHs).
Aspen is a common name for certain tree species; some, but not all, are classified by botanists in the section Populus, of the Populus genus.List of woods
This is a list of woods, in particular those most commonly used in the timber and lumber trade.Opinion polling for the 2015 United Kingdom general election
In the run up to the general election on 7 May 2015, various organisations carried out opinion polling to gauge voting intention. Results of such polls are displayed in this article. Most of the polling companies listed are members of the British Polling Council (BPC) and abide by its disclosure rules.
The date range for these opinion polls is from 6 May 2010 (the date of the previous general election) to 7 May 2015.
Most opinion polls cover only Great Britain (England, Scotland and Wales). Separate polls covering constituent countries of the UK and English regions are reported further below while polling of individual constituencies and groups of them (such as groups of marginals) is covered in a separate article.
In the event, the actual results proved to be rather different from those indicated by the opinion polls. Opinion polls conducted in the last few months of the campaign, and even in the last few days, had indicated a very close result between the Conservatives and Labour in terms of numbers of votes, suggesting that one of the main parties would have to form a perhaps complex coalition with smaller parties in order to govern.
However the actual results showed a stronger performance by the Conservatives, which gave them an overall majority, since Labour also had a weaker performance than the polls had suggested. When the exit poll was initially presented, some commentators and politicians doubted it, with Paddy Ashdown even declaring "If this poll is correct I will publicly eat my hat on your programme" in response to the apparently poor results for the Liberal Democrats. The exit poll was eventually proved to have in fact overestimated the Liberal Democrats' performance. If the Survation telephone poll (6 May) had been published it would have produced results within 1% of the election results.Populous
Populous or populus may refer to:
Populous (series), video game series
Populous (video game), first video game of the series
Populous (company), an architectural firm
Populus, a genus of plants
Populus Ltd, a market research companyPopulus alba
Populus alba, commonly called abele, silver poplar, silverleaf poplar, or white poplar, is a species of poplar, most closely related to the aspens (Populus sect. Populus). It is native to Morocco and the Iberian Peninsula through central Europe (north to Germany and Poland) to central Asia. It grows in moist sites, often by watersides, in regions with hot summers and cold to mild winters.Populus angustifolia
Populus angustifolia, commonly known as the narrowleaf cottonwood, is a species of tree in the willow family (Salicaceae). It is native to western North America, where it is a characteristic species of the Rocky Mountains and the surrounding plains. It ranges north to the provinces of Alberta and Saskatchewan in Canada and south to the states of Chihuahua, Coahuila, and Sonora in Mexico. Its natural habitat is by streams and creeks between 3,900 to 7,900 feet (1,200 to 2,400 m) elevation.Populus balsamifera
Populus balsamifera, commonly called balsam poplar, bam, bamtree, eastern balsam-poplar, hackmatack, tacamahac poplar, tacamahaca, is a tree species in the balsam poplar species group in the poplar genus, Populus. The genus name Populus is from the Latin for poplar, and the specific epithet balsamifera from Latin for "balsam-bearing".Populus balsamifera is the northernmost North American hardwood, growing transcontinentally on boreal and montane upland and flood plain sites, and attaining its best development on flood plains. It is a hardy, fast-growing tree which is generally short lived, but some trees as old as 200 years have been found.The tree is known for its strong, sweet fragrance, which emanates from its sticky, resinous buds. The smell has been compared to that of the balsam fir tree.Populus deltoides
Populus deltoides, the eastern cottonwood or necklace poplar, is a cottonwood poplar native to North America, growing throughout the eastern, central, and southwestern United States, the southernmost part of eastern Canada, and northeastern Mexico.Populus fremontii
Populus fremontii, commonly known as Fremont's cottonwood or the Alamo cottonwood, is a cottonwood (and thus a poplar) native to riparian zones of the Southwestern United States and northern through central Mexico. It is one of three species in Populus sect. Aigeiros. The tree was named after 19th century American explorer and pathfinder John C. Frémont.Populus grandidentata
Populus grandidentata, commonly called large-tooth aspen, big-tooth aspen, American aspen, or white poplar, is a deciduous tree native to eastern North America.Populus nigra
Populus nigra, the black poplar, is a species of cottonwood poplar, the type species of section Aigeiros of the genus Populus, native to Europe, southwest and central Asia, and northwest Africa.Populus sect. Aigeiros
Populus section Aigeiros is a section of three species in the genus Populus, the poplars. Like some other species in the genus Populus, they are commonly known as cottonwoods. The species are native to North America, Europe, and western Asia. In the past, as many as six species were recognized, but recent trends have been to accept just three species, treating the others as subspecies of P. deltoides.
They are large, deciduous trees that are 50–80 feet tall, distinguished by thick, deeply fissured bark and triangular-based to diamond-shaped leaves that are green on both sides (without the whitish wax on the undersides) and without any obvious balsam scent in spring. An important feature of the leaves is the petiole, which is flattened sideways so that the leaves have a particular type of movement in the wind.
Male and female flowers are in separate catkins, appearing before the leaves in spring. The seeds are borne on cottony structures that allow them to be blown long distances in the air before settling to ground.
The cottonwoods are exceptionally tolerant of flooding, erosion, and flood deposits filling around the trunk.
Although each of the three cottonwood species has a different leaf pattern, they all have the same general diamond leaf shape.Populus tremula
Populus tremula, commonly called aspen, common aspen, Eurasian aspen, European aspen, or quaking aspen, is a species of poplar native to cool temperate regions of Europe and Asia, from Iceland and the British Isles east to Kamchatka, north to inside the Arctic Circle in Scandinavia and northern Russia, and south to central Spain, Turkey, the Tian Shan, North Korea, and northern Japan. It also occurs at one site in northwest Africa in Algeria. In the south of its range, it occurs at high altitudes in mountains.The English name Waverly, meaning "quaking aspen", is both a surname and unisex given name.Populus tremuloides
Populus tremuloides is a deciduous tree native to cooler areas of North America, one of several species referred to by the common name aspen. It is commonly called quaking aspen, trembling aspen, American aspen, Quakies, mountain or golden aspen, trembling poplar, white poplar, popple, as well as others. The trees have tall trunks, up to 25 meters (82 feet) tall, with smooth pale bark, scarred with black. The glossy green leaves, dull beneath, become golden to yellow, rarely red, in autumn. The species often propagates through its roots to form large clonal groves originating from a shared root system. These roots are not rhizomes, as new growth develops from adventitious buds on the parent root system (the ortet).
Populus tremuloides is the most widely distributed tree in North America, being found from Canada to central Mexico. It is the defining species of the aspen parkland biome in the Prairie Provinces of Canada and extreme northwest Minnesota.
The Quaking Aspen is the state tree of Utah.Populus trichocarpa
Populus trichocarpa, the black cottonwood, western balsam-poplar or California poplar, is a deciduous broadleaf tree species native to western North America. It is used for timber, and is notable as a model organism in plant biology. A high-coverage genome sequence was published in 2006 and was the first tree genome to be sequenced. Long-read Pacbio sequencing enabled the assembly of all scaffolds in 2018.SPQR
SPQR (Latin: Senātus Populusque Rōmānus, "The Roman Senate and People", or more freely as "The Senate and People of Rome"; Classical Latin: [sɛˈnaː.tus pɔpuˈlus.kʷɛ roːˈmaː.nus]) refers to the government of the ancient Roman Republic. It appears on Roman currency, at the end of documents made public by inscription in stone or metal, and in dedications of monuments and public works.
The phrase commonly appears in the Roman political, legal, and historical literature, such as the speeches of Cicero and Ab Urbe Condita Libri ("Books from the Founding of the City") of Livy.Salicaceae
The Salicaceae are a family, the willow family, of flowering plants. The traditional family (Salicaceae sensu stricto) included the willows, poplar, aspen, and cottonwoods. Recent genetic studies summarized by the Angiosperm Phylogeny Group (APG) have greatly expanded the circumscription of the family to contain 56 genera and about 1220 species, including the Scyphostegiaceae and many of the former Flacourtiaceae.In the Cronquist system, the Salicaceae were assigned to their own order, Salicales, and contained three genera (Salix, Populus, and Chosenia). Now recognized to be closely related to the Violaceae and Passifloraceae, the family is placed by the APG in the order Malpighiales.Seal of Arkansas
The Arkansas State Seal was adopted in 1864 and modified to its present form on May 23, 1907. The outer ring of the seal contains the text "Great Seal of the State of Arkansas". The inner seal contains the Angel of Mercy, the Sword of Justice and the Goddess of Liberty surrounded by a bald eagle. The eagle holds in its beak a scroll inscribed with the Latin phrase "Regnat Populus", the state motto, which means "The People Rule". (The scroll read "Regnant Populi" prior to 1907.) On the shield of the seal are a steamboat, a plow, a beehive and a sheaf of wheat, symbols of Arkansas's industrial and agricultural wealth.