Subspecific variability of Tunisian wild populations of Capparis spinosa L.

Fifteen Tunisian wild populations of caper (Capparis spinosa L.) from different geographical regions, including inerm and thorny morphotypes were assessed for their phenotypical variation using eight morphological traits. The thorny type is restricted to the North of the country, while the inerm is wildly distributed from the North to the South. The data underwent an analysis of variance and a multivariate analysis. Significant differences among populations and among morphotypes for the eight descriptors were observed. The level of variation was high among populations belonging to the inerm type. The PCA and HAC groupings performed on all measured characters showed a clear discrimination between thorny and inerm morphotypes. The subclusters are concordant with the recent botanical subdivision of C. spinosa subsp. spinosa and C. spinosa subsp. rupestris (Sm.) Nyman. These two wild subspecies showed different ecological characteristics. These differences concerned the bioclimate and the soil proprieties, which the electrical conductivity (EC), the chemical composition (Na(+), Ca(++), Mg(++), SO4(--), Cl(-) and HCO(3)(-)) and the soil texture. In addition, the ecological location seems to a factor structuring the variability of the inerm populations.