A listserv to which I am a subscriber posted a question I've always wondered upon myself. Perhaps someone can enlighten:
"My hop vines climb with a lefthand spiral (which seems logical - I figured they would follow the sun as they rise), my pole beans with a righthand spiral. They have the same sun and sky exposure and are close to each other. ...I have not been able to find any references leading to information on the physiological cause for the spiral on plants. If I start a vine in the "wrong" direction, it "corrects" it.
Anyone know what induces the spiral?" Bob
Hat tip to Cathleen