Rumex verticillatus is aa aquatic perennial herb 40-100 cm tall, taprooted, colonial from a rhizome, usually unbranched below inflorescence; many-branched. Stipule (ocrea) membranous sleeve-like around stem above leaf stalk (Flora of North America 1993+).
Leaves alternate, 5-30cm long, 1-5 cm wide, flat, linear-lance shaped, narrowed to base, pointed at both ends, thin, somewhat rubbery texture; margins entire, sometimes wavy (undulate).
Flowers green, with 3 small, narrow outer valves (tepals) and 3 inner, broadly triangular valves (tepals) 0.4-0.6 cm long, 0.3-0.4 cm wide, almost as wide as long, edges appressed to adjoining valves forming a 3-winged flower/fruit, lower part of valve midrib a raised tubercle 2/3 as long as valve, minutely wrinkled (rugose) or pitted (punctate) near base, projecting slightly below base of valve; flower stalk 1.0-1.7 cm long, jointed near base, widest at top, 3-5 times as long as inner tepals; in whorled clusters of 10-15 flowers; inflorescence a panicle 20- 40 cm long, branches ascending to lax (Flora of North America 1993+); blooming June-Aug. (Hough 1983).
Fruit dry about 0.3 cm long, 0.2 cm wide; fruiting June-Sept. (Hough 1983).
Wetland status: OBL.
Frequency in NYC: Very infrequent.
Habitat: Pond edges. Swamps, bogs, marshes, wet meadows, irrigation ditches, wet alluvial woods.