Polygonum arifolium halberd-leaved tearthumb Polygonaceae POAR; Bx, pb, sf; R, t;

 

Polygonum arifolium.Rob Curtis.www.inaturalist.org

Polygonum arifolium.Rob Curtis.www.inaturalist.org. (Accessed 4/2014).

Polygonum arifolium is an annual vining herb, 1-2 m, stem with hooked prickles, slender, reclining on other vegetation; ocreae membranous. 

Leaves alternate, arrow-shaped, to 20 cm long, 15 cm wide, basal lobes triangular, divergent, hairs in tiny cushions below. 

Flowers pink, white or green, radially symmetrical, 5-parted, fused at base, petals (tepals) 0.25 cm, rounded on back, styles 2; blooming and fruiting Aug.-Sept. (Hough 1983). 

Fruit dry, one-seeded, achene, broadly lens-shaped, to 0.5 mm, shiny, brown. Seeds eaten by many birds and small mammals (Martin et al 1951). 

Wetland status: OBL. 

Frequency in NYC: Very infrequent. 

Origin: native. 

Habitat: Open marshes, pond edges.