Salix alba L.
Eng.: White willow. Spa.: Sauce blanco. Fre.: Saule blanc, osier blanc. Ara.: Khilaf, mektite, mektata, hud el ma, ud el mêê. Tam.: Talezzast amellat, tafeçant, tafsent.
Deciduous tree or shrub, dioecious, up to 25 m in height, irregular in shape. Trunk ± straight, robust, up to 1 m in diameter, with greyish-brown bark, almost blackish and longitudinally fissured in the older specimens. Branches extended-erect, rarely pendulous. Branchlets often pendulous, initially tomentose, then turning glabrous, green. Buds villous-silky. Leaves alternate, 5-13 × 1-3.5 cm, deciduous, clearly lanceolate, with serrated margin; at first densely villous-silky and at maturity glabrescent on the upper side and ± hairy on the underside, green on the upper side and whitish or glaucous-bluish on the underside. Petiole short, with simple glands at the junction with the leaf blade. Stipules small, similar to the leaves. Inflorescence in erect or slightly pendant aments, alternate, pedunculate, coeval with the leaves. Rachis villous and floral bracts of a single colour, caducous. Male flower with 2 nectaries and 2 stamens with free filaments. Female flower with only 1 nectary and sessile or subsessile ovary, glabrous. Fruit a capsule that opens into 2 ovoid valves, acute, which are curved backwards, just showing the seeds surrounded by numerous long white hairs, cottony.
Flowering:
February to May.
Fruiting:
April to June.
Habitat:
Along banks of rivers and streams with permanent or semipermanent waters, margins and islands of lakes and other wetlands, reaching 2,400 m in altitude. In thermomediterranean to supramediterranean bioclimatic floors.
Distribution:
Palearctic. In North Africa it has been cited as relatively common across the NW, from northern Tunisia (Mogods) to the High Atlas, missing from the high plateaux region and the Saharan Atlas. The citations of northern Libya seem to correspond to introduced specimens.
Observations:
Depending on the hairiness and leaf colour several varieties have been cited in North Africa, however not all authors recognise them. Varieties such as: S. alba var. caerulea (Sm.) Koch (S. caerulea Sm.), with glabrescent leaves on both sides and a clear glaucous-blue colour on the underside, which could be an introgression with S. fragilis; known from the mountains of Tlemcen and other sightings in the Middle Atlas, but its presence here seems doubtful. Given its ecology and distribution in the nearby Iberian Peninsula, and since there are some doubts of its presence in North Africa, S. fragilis L. is very likely to occur in the Mediterranean area of Maghreb. A species similar in size and appearance to S. alba, well differentiated by the presence of 2 nectaries in the female flowers, which are pedunculate (peduncle longer than the nectaries), adult leaves glabrous and branched glands at the junction of the leaf blade with the petiole (some specimens could have been confused with of S. alba var. caerulea). Other specimens that could have been wrongly attributed to S. alba are those of S. neotricha Goerz, which has female flowers with 2 nectaries and, most commonly, leaves that do not have glands in the area where the petiole is joined to the limb. In FAN 7: 42, Maire mentions the possibilty that S. neotricha is present in Morocco, based on a flowerless specimen found in the Beni Mansur River, near Berkine (Middle Atlas).
Conservation status:
S. alba is a relatively common and widespread species. It is not considered threatened. It is listed at a global level in the IUCN Red List of Threatened Species as Least Concern (LC) (Lansdown, 2014). S. neotricha is also common but currently it has not been assessed at a global level on the IUCN Red List of Threatened Species.