Polygonum perfoliatum is a creeping annual found on roadsides,
paths in rice paddies, or dry river beds. The stems grow to 1-2m
long and twine around other trees or weeds with sharp downward
prickles. Leaves are triangular, 2-4cm in length; their petioles,
shield-shaped, sit at the close-to-bases portion of the blades.
Ochreas are short, and the upper parts expand to grow round. From
stem tops and leaf-axils emerge racemes with masses of small green
flowers in them. At the bases of the racemes exist leaf-like bracts,
which is striking. Bloom time: July-October.