Populus

Some of the most easily identifiable fossils of this genus belongs to Poplus wilmattae, and comes from the Late Paleocene of North America about 58 million years ago.[9] However, fossils from the Cretaceous of this genus have been found in Tibet and Heilongjiang, China. [10]

Populus nigra in autumn

Populus × petrowskiana ("Czar's Poplar") in Heinola, Finland

• Populus section Populus – aspens and white poplar (circumpolar subarctic and cool temperate, and mountains farther south, white poplar warm temperate)
  • Populus adenopoda – Chinese aspen (eastern Asia)
  • Populus alba – white poplar (southern Europe to central Asia)
    • Populus × canescens (P. alba × P. tremula) – grey poplar
  • Populus davidiana – Korean aspen (eastern Asia)
  • Populus grandidentata – bigtooth aspen (eastern North America)
  • Populus luziarum – Jalisco, Mexico[11]
  • Populus primaveralepensis – Jalisco, Mexico[11]
  • Populus sieboldii – Japanese aspen (eastern Asia)
  • Populus tremula – aspen, common aspen, Eurasian aspen, European aspen, quaking aspen (Europe, northern Asia)
  • Populus tremuloides – quaking aspen or trembling aspen (North America)
• Populus section Aigeiros – black poplars, some of the cottonwoods (North America, Europe, western Asia; temperate)
  • Populus deltoides – eastern cottonwood (eastern North America)
  • Populus fremontii – Fremont cottonwood (western North America)
  • Populus nigra – black poplar (Europe), placed here by nuclear DNA; cpDNA places it in sect. Populus (including Populus afghanica)
    • Populus × canadensis (P. deltoides × P. nigra) – hybrid black poplar
    • Populus × inopina (P. nigra × P. fremontii) – hybrid black poplar

Leaves of Populus lasiocarpa

• Populus section Tacamahaca – balsam poplars (North America, Asia; cool temperate)
  • Populus angustifolia – willow-leaved poplar or narrowleaf cottonwood (central North America)
  • Populus balsamifera – Balsam poplar (northern North America) (= P. candicans, P. tacamahaca)
  • Populus cathayana – (northeast Asia)
  • Populus koreana J.Rehnder – Korean poplar (northeast Asia)
  • Populus laurifolia – laurel-leaf poplar (central Asia)
  • Populus maximowiczii A.Henry – Maximowicz' poplar, Japanese poplar (northeast Asia)
  • Populus simonii – Simon's poplar (northeast Asia)
  • Populus suaveolens Fischer – Mongolian poplar (northeast Asia)
  • Populus szechuanica – Sichuan poplar (northeast Asia), placed here by nuclear DNA; cpDNA places it in sect. Aigeiros
  • Populus trichocarpa – western balsam poplar or black cottonwood (western North America)
  • Populus tristis (northeast Asia), placed here by nuclear DNA; cpDNA places it in sect. Aigeiros
  • Populus ussuriensis – Ussuri poplar (northeast Asia)
  • Populus yunnanensis – Yunnan poplar (east Asia)
• Populus section Leucoides – necklace poplars or bigleaf poplars (eastern North America, eastern Asia; warm temperate)
  • Populus heterophylla – downy poplar (southeastern North America)
  • Populus lasiocarpa – Chinese necklace poplar (eastern Asia)
  • Populus wilsonii – Wilson's poplar (eastern Asia)
• Populus section Turanga – subtropical poplars (southwest Asia, east Africa; subtropical to tropical)
  • Populus euphratica – Euphrates poplar (North Africa, southwest and central Asia)
  • Populus ilicifolia – Tana River poplar (East Africa)
• Populus section Abaso – Mexican poplars (Mexico; subtropical to tropical)
  • Populus guzmanantlensis (Mexico) (may be conspecific with Populus simaroa)
  • Populus mexicana – Mexico poplar (Mexico)
• Intersectional hybrids
  • Populus × acuminata (P. angustifolia × P. deltoides) – lanceleaf cottonwood
  • Populus Pacific Albus[12] (North America)

Popular Populus variety G48 in Punjab, India; Jhalli Farms Village Niara/Hoshiarpur

In India, the poplar is grown commercially by farmers, mainly in the Punjab region. Common poplar varieties are:

• G48 (grown in the plains of Punjab, Haryana, UP)
• w22 (grown in mountainous regions, e.g., Himachal Pradesh, Pathankot, Jammu)

The trees are grown from kalam or cuttings, harvested annually in January and February, and commercially available up to 15 November.

Poplars are 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)).

In addition to the foliage and other parts of Populus species being consumed by animals, the starchy sap layer (underneath the outer bark) is edible to humans, both raw and cooked.[16]

• In many areas, fast-growing hybrid poplars are grown on plantations for pulpwood
• Poplar is widely used for the manufacture of paper.[17]
• It is also sold as inexpensive hardwood timber, used for pallets and cheap plywood; more specialised uses including matches and matchboxes and the boxes for Camembert cheese.
• Poplar wood is also widely used in the snowboard industry for the snowboard core, because it has exceptional flexibility, and is sometimes used in the bodies of electric guitars and drums.
• Poplar wood, particularly when seasoned, makes a good hearth for a bow drill.
• Due to its high tannic acid content, the bark has been used in Europe for tanning leather.[4]
• Poplar wood can be used to produce chopsticks or wooden shoes.
• Baking moulds from peeled poplar may be used in the freezer, oven, or microwave oven.[18]

In Pakistan, poplar is grown on a 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 for biocontrol of termites in crops.

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.

Rotor poplar and willow cuttings planter, planting a new nursery of poplar for biomass with short rotation

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.[19] In warmer regions like Italy this crop can produce 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.[20]

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.[21] Considering the relative cheap price, the process of making biofuel from SRC can be economically 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.[22]

Poplar was the most common wood used in Italy for panel paintings; the Mona Lisa and most famous early Italian Renaissance 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:[23] 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.

Lombardy poplars are frequently used as a windbreak around agricultural fields to protect against wind erosion.

Logs from the poplar provide a growing medium for shiitake mushrooms.[24]

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[25] and sewage sludge,[26][27] Polychlorinated Biphenyl (PCBs),[28] Trichloroethylene (TCE),[29] Polycyclic Aromatic Hydrocarbon (PAHs).[30]