i have a theory here....(smoke,sorry for repeating it in print...but i have to tell these guys too)

i'd like to think of them this way.imaigine the scenario of an enormous spaceship...y'know the typical sci-fi one....huge circular and saucer shaped.now that thing needs some kinda thrust to lift itself from the base.right?owing to it's circular base,it needs a lot of extremely powerful fans of some kind to lift it from the base....to give it that thrust.so maybe some of these spaceships chose to land on earth on these places and in the event of take-off,the thrusting force caused by the high pressure air from the fans would have caused the plants to bend down....if u notice,almost all such patterns are more-or-less circular....which further accertains my point.

Going to church no more makes you a Christian than standing in a garage makes you a car. ~ Garrison Keillor