Must have been a different show you were watching because I just checked the Mythbuster website and found this...

http://mythbustersresults.com/episode61

"
Polygraph tests indicate that all living things share some form of interconnected consciousness.

busted

Tests were done by connecting plants to a polygraph’s galvanometer, and then employing actual and imagined harm upon the plants or upon others in the plant’s vicinity. The galvanometer showed some spurious readings (showing some kind of reaction about 1/3rd of the time), so a much more accurate EEG machine was used. When Grant and Tory used a machine that dropped eggs randomly into boiling water, the plant had no reaction. Additionally, Tory’s leukocytes had no reaction when Kari shocked him with a stungun."