A perennial herb typical of permanent, still or slow-flowing mesotrophic to eutrophic waters, extending into brackish water in coastal grazing marshes. It also grows in a terrestrial form on wet mud as water levels drop. Lowland.
C. obtusangula was under-recorded for the 1962 Atlas. There is no evidence of any genuine change in its distribution.
Suboceanic Southern-temperate element.