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The visual characterization of argan trees (Argania spinosa L. Skeels) in their domain has always
distinguished the presence of two forms. However, there are five morphological types on the basis of
twenty-one characteristics of branching and growth observed in three natural populations in south west
Morocco e.i. Ait Melloul, Argana and Ait Baha. The morphological type spinely, less branched with long
branches is most abundant (31.1%). However, both morphological types, very little spiny, little branched
with very long shoots, and spiny, branched with short branches are less frequent. The other two forms,
very thorny and highly branched, with very short branches, and very spiny, very branched, with shoots
moderately long, have intermediate percentages. The length of the main branch, number of green shoots,
spiny green shoots, tertiary shoots, and green shoot angle were the discriminating characters between the
five morphological types. Variability of shapes and frequencies in the three populations reflects potential
diversity in physiognomy of trees, indicating differential behavior of main branches of trees within the
same population. Type V is not represented in the mountainous site characterized by cold autumn and
winter was probably due to low temperatures, which can induce a slowdown in physiological budding
process and growth of branches.
Keywords: multivariate analysis; Argania spinosa; model of branching; growth, branching; tree shape.