One-seed Bur Cucumber (Sicyos angulatus)

6/16/12 PL DE
Picture of the white flowers at a later date, I hope. It blooms from late summer to early fall and lasts about 3 weeks.
http://plants.usda.gov/java/profile?symbol=SIAN&photoID=sian_001_avd.tif

http://www.illinoiswildflowers.info/savanna/plants/bur_cuke.htm