Populus euphratica Oliv.
Eng.: Euphrates poplar, desert poplar. Spa.: Álamo moro. Fre.: Peuplier de l’Euphrate. Ara.: Sefsaf, safsaf, merssiche, requeiqab (Egypt).
Deciduous tree, dioecious, up to 20 m in height, very irregular in shape. Trunk ± straight and smooth, sometimes very tortuous and may reach exceptionally up to 1 m in diameter. Bark greyish-whitish. Branches pubescent when young, turning glabrous, yellowish-brown. Buds with 2 scales, slightly or not at all viscous, glabrescent. Leaves alternate, glaucous, concolourous, glabrous, longly petiolate, very polymorphous. In young trees leaves are commonly lanceolate, entire, sometimes toothed in the upper half. In adult trees, especially towards the top, the leaves are usually reniform, sometimes wider than long, entire in the lower half and irregularly dentate-lobulate in the upper half. Frequently there are also ± rhomboid leaves, entire in the lower half and ± coarsely dentate towards the apex. Flowers in pendant aments, short, forming ± dense racemes. Flowers of male aments with short pedicels (2-4 mm), disk membranous, glabrous and caducous, with 12-14 stamens with purple anthers. Flowers of female aments with pedicels much longer (8-12 mm), disk similar to male flowers and ovary ending in 3 large purple stigmas. Fruit an ovoid-elongated capsule, smooth, coriaceous, dehiscent into 2-3 valves, containing numerous seeds with whitish hairs.
Flowering:
February to April.
Fruiting:
April to June.
Habitat:
Riverbanks of permanent or semipermanent watercourses, in Mediterranean or desert climate. It can tolerate drought and a relatively high degree of salinity compared to other species for the genus.
Distribution:
Species with a very broad and disjunct distribution, from North Africa to central Asia (Himalaya, China, Mongolia), missing from large areas in between. Introduced in an irrigation canal of somewhat brackish water near Elche (Alicante, Spain). In North Africa it is very rare, scattered between eastern Morocco (Muluya, Msum, Uizert, Bu-Adil, Ziz Rivers, etc.) and western Algeria (Lalla Maghnia, Ghazaouet, Hamman-el-Gelta, Tralimit, Mya Rivers, etc.). It seems to have became extinct in Tunisia and Libya but it still found in Egypt (oasis of Siwa).
Observations:
Due to its extensive range and isolated development of the existing small populations, several varieties have been differentiated. The following varieties grow in the study area: P. euphratica var. mauritanica (Dode) Maire (P. mauritanica Dode), with glabrescent buds and capsules, and P. euphratica var. bonnetiana (Dode) Maire (P. bonnetiana Dode), with pubescent buds and lanate capsules; the latter is also differentiated by a soft yellowish tint to the leaves.P. euphratica is a very rare and primitive species. Its wood is reddish and hard, very different from the other trees in the genus. Its closest relatives have long been extinct and appear be P. mutabilis from the Middle Tertiary in central Europe and North America and P. massiliensis from the Miocene in SE France. This exceptional tree, which can be considered a living fossil, has great biogeographical and aesthetic value, and despite its slow growth, it should be used more in the regeneration of riverbanks in North Africa. In addition to the interest of recovering an increasingly rare species, this tree is well suited to repopulate margins of permanent or temporary wetlands, due to its greater tolerance to drought and salinity compared to other species of the same genus.
Conservation status:
A rare but widely distributed species. It is not considered threatened. Currently, it has not been assessed at a global level in the IUCN Red List of Threatened Species. In Algeria it is included in the List of protected non cultivated flora (Executive Decree 12-03 on 4-Jan-2012). In the Red List of vascular plants of Egypt (Flora Aegyptiaca Vol 1, 2000) it is listed as “Endangered”.