E. septangulare: aquatic: stem varying in height according to the depth of the water, usually with six or eight, rarely seven or ten angles, each corresponding with a bundle of vessels surrounding a central bundle; scapes striated, longer than the cellular compressed subulate glabrous leaves; flowers four-cleft, hairy at the extremities, each flower with a broad, blunt, black scale in front, shorter and broader than the flower. - Pipewort. - Peaty lakes and pools.