Eriocaulon quinquangulare is a spectacular, still very rare Eriocaulon species. It is produced in nurseries as emersed (terrestrial) plant. 
 
It is a demanding plant which needs high light, proper fertilization and good CO2 supply. They are normally planted in cluster in the mid and fore ground of the tank. It is also great for paludariums and ripariums as it grows quite easily as emersed plant.