Morpho-anatomical diversity of five species of the genus Asparagus (Asparagaceae) from Algeria

Five species of the genus Asparagus are recognized in the flora of Algeria: A. acutifolius L., A. albus L., A. horridus L., A. officinalis L., and the endemic A. altissimus Munby. The chorology of each of these species is fairly well known. In this study, morphological variation and the anatomical features of the cladodes have been evaluated in respect to each taxonomic unit and ecogeographical distribution and they suggest distinct adaptive strategies. Analyses have been performed on twenty-nine natural populations sampled along the east-west bioclimatic gradient of Northern Algeria. Multivariate analysis based on the main diagnostic descriptors underlines the interspecific differentiation particularly with respect to the stigma type, bifid versus trifid, shape of flowers, color of berry, and the number of cladodes in a fascicle. For each species, the anatomy of the cladodes is unique, unlike that of stems and roots. Interspecific differentiation was observed in the form of cross-sections of the cladode, thickness of the cuticle, shape of epidermal cells, number of vascular bundles and presence of raphides. Morphological and anatomical traits of the cladode constitute important interspecific criteria within the genus Asparagus.