Variability in leaf size and shape in three natural populations of Argania spinosa (L.) Skeels

Shape of simple and grouped leaves in argan (Argania spinosa (L.) Skeels), based on visual characterization and principal component analysis was studied in three populations in south west Morocco: Ait Melloul (AM), Argana (AR) and Ait Baha (AB). Five leaf traits: length, width, petiole length, ratio (width / length) and area (length x width) were observed. In both type of leaves, four forms were defined: shape obovate with obtuse apex (OT), spatulate with obtuse apex (ST), lanceolate with acute apex (LA) and lanceolate shape with mucronate apex (LM). In all three localities, OT form was more common (78.9%) than ST form in which percentage was about 13.3%. LA and LM forms were lowly represented. Forms LA and LM were clearly distinguished from other shapes by blade apex. LA was characterized by acute apex, while LM was characterized by a mucronate apex. OT form was shorter, wider, with shorter petiole. ST form was longer and narrower, with longer petiole than OT. Morphometric traits explain most than 98.9% of the total variability in simple and grouped leaves. Leaf traits used seem to describe the variability observed for all shapes identified. The leaf can be considered as a microcopy of plant, variation in leaf morphology can reflect plant capacity to acquire, use and conserve resources since the argan tree is a source of food irremplassable in the southern regions.