Larry H. McCormick, Pennsylvania State University. Finger in lower left provides size scale. Larry H. McCormick, Pennsylvania State University. Polygonum perfoliatum is an annual scandent herb with elongated, branched stems to 2 m long. Stems are slender, have short retrorse prickles, and, when in the sun, may be reddish.
Petioles are as long as leaf blades and have retrorse prickles.
The upper leaves are represented by the foliaceous ocrea. 3 mm wide and long. In fruit, the spike looks like an odd, iridescent-blue blackberry. P. perfoliatum 1. P. meisnerianum 2.