The polysaccharidic mucilage is a widespread plant trait with diverse features, often present around plant structures in contact with the environment, providing numerous functions including protection and adhesion. In myxodiasporous species, a mucilage is released upon the imbibition of the seed (myxospermy) or the fruit (myxocarpy), and therefore can play roles in the early seedling stages. It is unclear whether myxodiaspory has one or multiple evolutionary origins and why it disappeared in several species. Here, we summarize the recent advances on (i) the mucilage and mucilage secretory cell diversity, (ii) the evolution of the molecular actors involved in myxospermy underlying the observed inter- and intra-species natural diversity and (iii) the recently identified ecological functions. At the intra-species level, a high polymorphism was detected for a few genes in relation to the observed morphological diversity. Well characterized transcriptions factors interact in master regulatory complexes to balance carbon partitioning in Arabidopsis thaliana seeds. These transcription factors were sequentially recruited during seed plant evolution to control diverse traits including myxospermy, and their functions in seeds seem to be conserved across Rosids. Historically, the ecological functions of seed mucilage were mostly related to germination and seed dissemination but recently some exosystemic functions were uncovered such as soil micro-organism control and plant establishment support.