Populus L.
Genus of about 72 species, 4 of which reach the North of Africa, with very unequal distributions and abundance. P. nigra and P. alba grow scattered almost throughout the whole Mediterranean area; P. euphratica is much rarer and it is restricted to very few rivers located in eastern Morocco and western Algeria. P. tremula is even rarer, only known from the mountains of Kabylia.
Ruiz de la Torre, J. & Ceballos, L. 1971. Árboles y arbustos de la España peninsular. Esc. Tec. Sup. Ingenieros de Montes. Madrid.
Key to species
1 Leaves with the same colour on both sides, very polymorphic. Young leaveslanceolate, adult leaves wider than long. Nectariferous disk caducous Populus euphratica
1 Leaves green ± dark on the upper side, light green to white on theunderside, similar in shape and size. Nectariferous disk persistent 2
2 Leaves with crenate-serrate margin, light green on the underside. Young shoots and winter buds glabrescent and very viscous Populus nigra
2 Leaves coarsely dentate or lobulate, white or light green on the underside.Young shoots and winter buds pubescent to tomentose, turning glabrescent, only slightly or none at all viscous 3
3 Adult leaves ± tomentose and white on the underside, petioles ± cylindrical in cross section, trunks whitish Populus alba
3 Adult leaves glabrous and light green on the underside, petioles flattened in cross section,trunks not whitish Populus tremula
Updated by: F. Alcaraz & J. Charco.