This study is based on a ruderal species: Malva subovata = Lavatera maritima which should normally grow in the littoral, under maritime influence. Its presence in the matorrals is highlighted for the first time. as it has been found far from its natural habitat. The comparison of the different biological and morphological spectra shows the importance of the therophytes that confirms the phenomenon of degradation. This degradation shows a depletion of the floristic procession, especially concerning sylvatic species which have given way to ephemeral therophytes and chamæphytes. Despite the presence of a shrubby layer, it is no longer a question of a forest ecosystem but of a pre-forest ecosystem. To better understand the characteristics of this Malvaceae in terms of resistance and adaptation in matorrals, we often use the phytomass of all anthropozoic formations and more specifically the phytomass of the species that characterize this group.  In our case, this is Malva subovata. The results of the morphometric study constitute a basic element for the evaluation of the adaptive potential of our Lavatère against the degradation factors.