Persicaria sagittata (L.) H.Gross
Family: Polygonaceae
arrow vine, arrow-leaved tearthumb
Persicaria sagittata image
Merel R. Black  
Etymology: Persicaria: peach-like, the medieval name for knotweed
Plants: climbing or tangling, annual, 3'-6' long, slender forb; 4 -angled stems very prickly
Leaves: alternate; triangular with wide, flaring lobes at the base
Flowers: pink to white, 5-parted, 3/8" long, egg-shaped, stalkless, petals and petal-like sepals; inflorescence short, rounded, uninterrupted clusters both terminal and from the leaf axils; blooms Aug.-Sept.
Fruits: dry seed
Habitat: wet; marshes, swamps, wet meadows