A. Damasonium: aquatic, annual; leaves glabrous, radical, long-stalked, ovate or oblong; flower-stems erect, 3-9 inches high, bearing a terminal umbel and a few whorls of flowers lower down, the inner segments of the perianth delicate, white, with a yellow spot at the base; carpels six, radiating horizontally like a star. - Watery ditches and pools. Fl. June, July.