Coastal plants tends to harbor characteristics as wide range expansion by water seed dispersal and formation of long stolons to propagate clonal ramets, expecting poor phylogeographical structure and low genetic diversity within a population. Objectives of this review are focused to suggest a guiding principle to vegetative restoration and conservation of coastal plants. Phylogeographical studies on beach morning glory and beach pea suggested no geographical structure possibly due to long distance seed dispersal, while genetic diversity in each population was high suggesting high contribution of seed germination by outcrossing. In case of wild radish, populations along Japanese Islands were clearly demarcated north and south at islands of Yakushima and Tanegashima. The north-south lineage divergence was triggered by the vernalisation response, which may be reinforced by reproductive success in each habitat environment. Knowledge of coastal plants phylogeography and population genetics has been limited, and we should carefully design vegetation restoration by introducing neighboring populations and/or introduction of seed propagations to keep genetic diversity and shaded phylogeographical structure for the time.