Potamogeton spirillus spiral pondweed Potamogetonaceae POSP; R;

Potamogeton spirillus.C. B. Hellquist.potamogetonaceae e-monocot.org.

Potamogeton spirillus.C. B. Hellquist.potamogetonaceae e-monocot.org.

Potamogeton spirillus is a perennial, submerged monocotyledon, rooted aquatic, stems to 1.5 m long, bushy-branched or elongate. 

Leaves alternate, submerged leaves linear, 1-8  cm long, to 0.2 cm wide, 1-3 veined, tip usually blunt; floating leaves, when present, usually oval, 0.7-3.5 cm long, 0.2-1.3 cm wide, veins 5-13. 

Flowers minute in spikes; submerged spikes round, with 1-8 fruits on curved-back stalks to 0.3 cm long; aerial spikes cylindrical to 1.3 cm long with 4-35 fruits. 

Fruit about 0.2 cm long sharply keeled on back, with a coiled pattern on sides and depressed center (shape of embryo); blooming and fruiting July-Nov. (Hough 1983). 

Wetland status: OBL. 

Frequency in NYC: Very infrequent. 

Origin: Native. 

Habitat: Quiet water.