Do plants feel pain?

I'm sitting here avoiding doing the work I'm supposed to be doing, but I've got a really good reason... Construction workers outside my window are tearing up the grounds around the building across the street. Watching them tear up the shrubbery this morning made me wonder if they were going to get to the 3 story tall cedar next to the building, and sure enough it just went down.

Watching the big truck with the shovel on the end (yea, I'm a scientist not an engineer) wrestle this thing to the ground was intense. I was actually saddened by the death of this tree and wondered if it felt anything as it was being ripped to shreds. Of course I have the internet at my finger tips and I found this video of a plant being tortured while hooked up to a polygraph.

A polygraph measures the galvanic skin response or the change in electrical resistance between two electrodes hooked to something (i.e. a liar, or in this case, a plant under duress). They measured a response whether the plant was merely being slapped, or was being blasted by a fire extinguisher. Now, a lot of work has been done by various men to show that when a human is distressed by something (even unconsciously) their galvanic skin response registers a change. I'm not sure enough work has been done in the field of plant psychology to say that this is also true of plants. Although, it makes absolute sense that a tree in danger would have some means to communicate to it's neighbors that something dangerous is happening.

This does bring to mind; however, an almost buried Deep Thoughts quote by Jack Handy:

If trees could scream, would we be so cavalier about cutting them down? We might, if they screamed all the time, for no good reason.