Envoy at 05:51, 28 October 2007

2007-10-28T05:51:51Z

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{{otheruses1|woody plants of the genus '''Populus'''}}
{{Taxobox
| color = lightgreen
| name = Poplar, Aspen, Cottonwood
| image = Populus-trichocarpa.JPG
| image_width = 250px
| image_caption = Western Balsam Poplar foliage
| regnum = [[Plant]]ae
| divisio = [[Flowering plant|Magnoliophyta]]
| classis = [[Dicotyledon|Magnoliopsida]]
| ordo = [[Malpighiales]]
| familia = [[Salicaceae]]
| genus = '''''Populus'''''
| genus_authority = [[Carolus Linnaeus|L.]]
| subdivision_ranks = Sections
| subdivision =
Sect. ''[[Aspen|Populus]]''<br/>
Sect. ''[[Cottonwood|Aegiros]]''<br/>
Sect. ''[[Balsam poplar|Tacamahaca]]''<br/>
Sect. ''[[Necklace poplar|Leucoides]]''<br/>
Sect. ''[[subtropical poplars|Turanga]]''
}}
'''''Populus''''' is a genus of trees which includes the [[cottonwood]]s, poplars, and [[aspen]]s, all of which are sometimes termed '''poplars''' (in some areas "popple").

Poplars are [[deciduous]], and the leaves turn bright gold to yellow before they fall during [[autumn]]. The leaves of many poplars, including the cottonwoods and aspens (but not the balsam poplars), have laterally-flattened stems, so that breezes easily cause the leaves to wobble back and forth, giving the whole tree a "twinkling" appearance in a breeze.

Like willows, many poplars have very strong and invasive root systems, so they must not be planted too close to houses or water pipes as they will crack walls and pipes in their search for moisture.

Poplars of the cottonwood section are often wetlands or [[riparian]] trees. The aspens are among the most important [[Boreal ecosystem|boreal]] broadleaf trees.

Poplars and aspens are important food plants for the [[larva]]e of a large number of [[Lepidoptera]] species - see [[List of Lepidoptera that feed on Poplars]].

==Classification==
[[Image:Populus nigra-bekes.jpg|thumb|right|200px|A fastigiate Black Poplar cultivar of the Plantierensis Group, in [[Hungary]]]]
[[Image:poplartree.jpg|frame|right|A poplar in autumn colours]]

*'''''Populus'' section ''Populus'' - [[aspen]]s and white poplar.''' Circumpolar subarctic and cool temperate, and mountains farther south (white poplar warm temperate)
**''[[Populus tremula]]'' - Common Aspen, Trembling Aspen or Eurasian Aspen. Europe, northern Asia.
**''[[Populus tremuloides]]'' - Quaking Aspen or Trembling Aspen. North America.
**''Populus grandidentata'' - Bigtooth Aspen. Eastern North America.
**''Populus adenopoda'' - Chinese Aspen. Eastern Asia.
**''Populus sieboldii'' - Japanese Aspen. Eastern Asia.
**''Populus alba'' - [[White Poplar]]. Southern Europe to central Asia.
***''Populus × canescens'' (''P. alba × P. tremula'') - [[White Poplar#Cultivation|Grey Poplar]]
*'''''Populus'' section ''Aegiros'' - black poplars or [[cottonwood]]s.''' North America, Europe, western Asia; temperate
**''Populus nigra'' - [[Black Poplar]]. Europe.
***''Populus × canadensis'' (''P. nigra × P. deltoides'') - [[Black Poplar|Hybrid Black Poplar]]
**''Populus deltoides'' - [[Eastern Cottonwood]]. Eastern North America.
**''Populus fremontii'' - Fremont Cottonwood. Western North America.
**''Populus petrowskyana'' - Russian Poplar. Europe/Asia.

*'''''Populus'' section ''Tacamahaca'' - [[balsam poplar]]s.''' North America, Asia; cool temperate
**''Populus angustifolia'' - Willow-leaved Poplar or Narrowleaf Cottonwood. Central North America.
**''[[Populus balsamifera]]'' - Ontario Balsam Poplar. Northern North America.
**''[[Populus trichocarpa]]'' - Western Balsam Poplar or Black Cottonwood. Western North America.
**''Populus laurifolia'' - Laurel-leaf Poplar. Central Asia.
**''Populus simonii'' - Simon's Poplar. Northeast Asia.
**''Populus maximowiczii'' - Maximowicz' Poplar. Northeast Asia.

*'''''Populus'' section ''Leucoides'' - [[necklace poplar]]s or bigleaf poplars.''' Eastern North America, eastern Asia; warm temperate
**''Populus heterophylla'' - Swamp Cottonwood. 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. Southwest Asia.
**''Populus ilicifolia'' - Tana River Poplar. East Africa.

*'''''Populus'' section ''Abaso'' - Mexican poplars.''' Mexico; subtropical to tropical
**''Populus mexicana'' - Mexico Poplar. Mexico.

==Flowers==
The flowers are [[dioecious]] and appear in early spring before the leaves. They are borne in long, drooping, sessile or pedunculate aments which are produced from buds formed in the axils of the leaves of the previous year. The pistillate aments lengthen very considerably before maturity. The flowers are solitary, each one seated in a cup-shaped disk which is borne on the base of a scale which is itself attached to the rachis of the ament. The scales are obovate, lobed and fringed, membranous, hairy or smooth, usually caducous. The staminate flowers are without calyx or corolla and consist simply of a group of stamens, four to twelve, or twelve to sixty, inserted on a disk; filaments short, pale yellow; anthers oblong, purple or red, introrse, two-celled; cells opening longitudinally.<ref name=Keeler>{{cite book
| last =Keeler
| first =Harriet L.
| title =Our Native Trees and How to Identify Them
| publisher =Charles Scriber's Sons
| date =1900
| location =New York
| pages =410-412 }}</ref>

The pistillate flower is equally destitute of calyx and corolla and consists of a one-celled ovary seated in a cup-shaped disk. The style is short, stigmas two to four, variously lobed; ovules numerous. The fruit is a two to four-valved capsule, ripening before the full development of the leaf; greenish or reddish-brown. The seed is light brown and surrounded by a tuft of long, soft, white hairs.<ref name=Keeler />

==Cultivation and uses==
Fast-growing [[hybrid]] poplars are grown on [[plantation]]s in many areas for [[pulpwood]] and used for the manufacture of [[paper]]. The wood is generally white, often with a slightly yellowish cast. It is also sold as inexpensive hardwood [[timber]], used for [[pallet]]s and cheap [[plywood]]; more specialised uses include [[match]]es and the boxes in which [[Camembert (cheese)|camembert cheese]] is sold. Poplar wood is widely used in the [[snowboard]] industry for the snowboard "core", because it has exceptional flexibility.

Poplar was the most common wood used in [[Italy]] for [[panel painting]]s; the [[Mona Lisa]] and indeed most famous Early Renaissance Italian paintings are on poplar.

Due to its [[tannic acid]] content, the bark has been used in Europe for tanning leather.<ref name=Keeler />

There has been some interest in using poplar as an [[energy crop]]/[[biofuel]], particuarly in light of its high energy in/energy out ratio, large carbon mitigation potential and fast growth.

In the September 2006 issue of ''[[Science (journal)|Science]]'', it was announced that a species of poplar, ''[[Populus trichocarpa]]'', was the first tree to have its full [[DNA]] code sequenced (published in full [http://genome.jgi-psf.org/Poptr1_1/Poptr1_1.home.html here]).

Poplar is also a wood that, particularly when seasoned, makes a good hearth for a [[bow drill]]. Poplar was picked as the material for the bones of "Buster", the crash test dummy used in the TV show [[MythBusters]], after some experiments revealed that it fractures under approximately the same loads as human bone. Poplar is sometimes used in the bodies of [[electric guitar]]s and [[drum]]s.

''Populus'' is among the oldest type of dicotyledonous plants. When [[sequoia]]s, [[pine]]s and [[cycad]]s made up the bulk of the [[Cretaceous]] forests of Greenland, the poplar alone of deciduous trees was present.<ref name=Keeler />

== References ==
<references/>

==External links==
*[http://www.peupliersdefrance.org/ Poplar cultivation in Europe]
*[http://www.cirrusimage.com/tree_balsam_poplar.htm Balsam Poplar - ''Populus balsamifera''] Large-format diagnostic photos and information on poplar hybrids.

{{Commons|Populus}}

[[Category:Salicaceae]]
[[Category:Trees]]

Poplar - Revision history

Envoy at 05:51, 28 October 2007