Calligonum is a genre that plays an important role in the ecological and economic Tunisian desert. studies conducted on this are very rare, especially North African species.For this reason that this work is an introduction to organic and ecological future studies to develop this kind began disappearing. study of three species colonizing the Tunisian desert shows a wide genetic, morphological, anatomical and phonological diversity. but this study also shows that there is a certain similarity between them which confirms their relation.