Populus alba L., Sp. Pl. 1034 1753. (Syn: Leuce alba (L.) Opiz; Populus acerifolia Lodd. ex Loud.; Populus aegyptiaca Hort. ex W. Baxt.; Populus alba var. hickeliana (Dode) Fiori; Populus alba var. integrifolia Ball; Populus alba subsp. major (Mill.) R. Kam.; Populus alba var. microphylla Maire; Populus alba subsp. nivea (Willd.) Maire & Weiller; Populus alba var. nivea Ait.; Populus alba var. subintegerrima Lange; Populus arbeel Curt.; Populus arembergiana Hort. ex Dippel; Populus arembergica Lodd. ex Loud.; Populus belgica Lodd. ex Loud.; Populus candicans Lodd. ex Loud.; Populus excelsa Salisb.; Populus grisea Lodd. ex Loud.; Populus hickeliana Dode; Populus hickeliana var. tremulifolia Dode & Sennen; Populus intermedia Mert. ex Loud.; Populus major Mill.; Populus nivea (Ait.) Willd.; Populus palmata Hort. ex Loud.; Populus pendula Hort. ex Steud.; Populus pseudonivea Grossh.; Populus quercifolia Hort. ex Loud.; Populus schischkinii Grossh.; Populus schischkinii Grossh.; Populus subintegerrima (Lange) Sennen & Mauricio; Populus subintegerrima var. berkanensis Sennen & Mauricio; Populus viminalis Hort. Par. ex Poir.) as per Catalogue of life;
Albania, Austria, Bulgaria, Czech Republic, Slovakia, Germany, Greece (incl.
Kiklades), Crete, East Aegaean Isl., Rhodos, Hungary, Italy, Slovenia, Croatia,
Bosnia & Hercegovina, Montenegro, Serbia & Kosovo, Macedonia, Poland,
Romania, N-, C-, W- & E-European Russia, Belarus, Ukraine, Estonia (I),
Sardinia, Belgium (I), England (I), Corsica (I), Denmark (I), France (I),
Switzerland (I), Netherlands (I), Spain, Portugal, Northern Caucasus, Georgia
[Caucasus], Armenia, Azerbaijan, Siberia (W-Siberia), Kazakhstan, Kyrgyzstan,
Turkmenistan, Uzbekistan (I), Morocco, Algeria, Tunisia, Libya, South Africa
(I), trop. Africa (I), China (Xinjiang), China (I), Japan (I), Korea (I), Turkey
(E-Anatolia, Inner Anatolia, N-Anatolia, NE-Anatolia, NW-Anatolia: Bithynia,
S-Anatolia, SSW-Anatolia, SW-Anatolia, W-Anatolia, WN-Anatolia), European
Turkey, Iran (NE-Iran: Mts., S-Iran), Azores (I) (Terceira (I), Graciosa (I)),
Madeira (I) (Madeira Isl. (I)), Canary Isl. (I) (Fuerteventura (I), Gran Canaria
(I), Tenerife (I), La Gomera (I), La Palma Isl. (I)), USA (I) (Alabama (I),
Arkansas (I), California (I), Colorado (I), Connecticut (I), District of
Columbia (I), Delaware (I), Florida (I), Georgia (I), Iowa (I), Idaho (I),
Illinois (I), Indiana (I), Kansas (I), Kentucky (I), Louisiana (I),
Massachusetts (I), Maryland (I), Maine (I), Michigan (I), Minnesota (I),
Missouri (I), Mississippi (I), Montana (I), North Carolina (I), North Dakota
(I), Nebraska (I), New Hampshire (I), New Jersey (I), New Mexico (I), Nevada
(I), New York (I), Ohio (I), Oklahoma (I), Oregon (I), Pennsylvania (I), Rhode
Island (I), South Carolina (I), South Dakota (I), Tennessee (I), Texas (I), Utah
(I), Virginia (I), Vermont (I), Washington State (I), Wisconsin (I), West
Virginia (I), Wyoming (I)), Canada (I) (British Columbia (I), Manitoba (I), New
Brunswick (I), Nova Scotia (I), Ontario (I), Prince Edward Isl. (I), Quebec
(I)), Mexico (I), Bolivia (I), Argentina (I), Australia (I) (South Australia
(I), Queensland (I), New South Wales (I), Victoria (I), Tasmania (I))
as per Catalogue of life (Populus alba subsp. alba);
Iran (EC-Iran, NE-Iran: Mts., N-Iran, Iranian Aserbaijan, W-Iran), Afghanistan
(Badghys, Herat, Kabul, Kunar / Nuristan, Paktia / Khost), Pakistan
(Baluchistan, Quetta, Waziristan, Kurram, Chitral, Swat, Gilgit, Baltistan,
Astor), Jammu & Kashmir (Hazara, Murree, Kashmir),
Kazakhstan, Tajikistan,
as per Catalogue of life (Populus caspica (Bornm.) Bornm syn. of Populus alba L. as per POWO);

Populus alba, commonly called abele,[1][2] silver poplar,[1][2] silverleaf poplar,[1][2] or white poplar,[1][2] is a species of poplar, most closely related to the aspens (Populus sect. Populus).  

It is native from 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.[3][4]
It is a medium-sized deciduous tree, growing to heights of up to 16-27 m (rarely more), with a trunk up to 2 m diameter and a broad rounded crown. The bark is smooth and greenish-white to greyish-white with characteristic diamond-shaped dark marks on young trees, becoming blackish and fissured at the base of old trees. The young shoots are covered with whitish-grey down, including the small buds. The leaves are 4-15 cm long, five-lobed, with a thick covering of white scurfy down on both sides but thicker underneath; this layer wears off the upper side but not the lower, which stays white until autumn leaf fall. Larger, deeply lobed leaves are produced on fast-growing young trees, and smaller, less deeply lobed leaves on older, slow-growing trees. The flowers are catkins up to 8 cm long, produced in early spring; they are dioecious, with male and female catkins on separate trees; the male catkins are grey with conspicuous dark red stamens, the female catkins are greyish-green. The female catkins lengthen to 8–10 cm after pollination, with several green seed capsules, maturing in late spring to early summer. It also propagates by means of root suckers growing from the lateral roots, often as far as 20-30 m from the trunk, to form extensive clonal colonies.[4][5]
It requires abundant light and ample moisture, and stands up well to flood water and slightly acidic soils.
Its green-and-white leaves makes it an effective ornamental tree but the root suckers may cause problems in some situations. It is very attractive as an open-grown tree in water meadows, and, because of its extensive root system and tolerance of salt, is also planted to strengthen coastal sand dunes.[6]
 (From Wikipedia on 21.2.14)



It would be interesting to fix whether this plant should actually be named as Populus alba L. or P. caspica (Bornm.) Bornm.
Although Flora of Pakistan treats latter as synonym of former, The Plant List considers latter as unresolved, but there several recent publications treating two as distinct

In Flora Iranica, Nauman (1969) was of opinion that Populus alba L. is confined to Europe, N. Africa and Anatolia and does not extend to Caucasus, Transcaucasia, Persia, Afghanistan, Pakistan and Central Asia and it is replaced by P. caspica Bornm. in those regions. But after studying the type specimen Populus alba of Linnaeus (Upsala) and the specimen of India and central Asia, I found that both are similar species. I visited several herbaria in India and a few major herbaria in US but could not get a single specimen of Populus caspica. Unfortunately I don’t have any opportunity to visit any herbarium of Middle East so that I could study P. caspica. No images of type and other herbarium material are available in the web as well. So now it is not possible without studying the type and authentic specimen to conclude a decision.

Thanks … for information. Hope it is resolved soon.



POWO  Catalogue of life (Populus alba subsp. alba) Catalogue of life (Populus caspica (Bornm.) Bornm syn. of Populus alba L. as per POWOGRIN  Flora of China  Flora of Pakistan  Wikipedia
The Plant List Ver.1.1  Flora of China  FOC illustration  Flora of Pakistan  FOP illustration