Can plants sense human intentions?

Question

Cleve Backster's experiments on the ability of plants (and even microbes) to react to human thought have been popularized by the book The Secret Life of Plants.

There's a very interesting interview with Backster in The Sun Magazine:

I thought that if I put the galvanic-skin-response detector of the polygraph at the end of the leaf, a drop in resistance would be recorded on the paper as the moisture arrived between the electrodes. [...] I noticed something on the chart that resembled a human response on a polygraph: not at all what I would have expected from water entering a leaf. Lie detectors work on the principle that when people perceive a threat to their well-being, they respond physiologically in predictable ways. [...] at thirteen minutes, fifty-five seconds chart time, the thought entered my mind to burn the leaf. I didn't verbalize the idea; I didn't touch the plant; I didn't touch the equipment. Yet the plant went wild. The pen jumped right off the top of the chart. The only thing it could have been reacting to was the mental change.

If true, the implications are staggering. Yet, I've not been able to find conclusive rebuttal of his experiments. Considering the implication, you'd expect this question to be resolved conclusively one way or the other by now.

Can anyone provide links to results of independent experiments? Thanks.

Answer 1

Cleve Backster's work was unreproducible by himself or others, and has been discarded as a working hypothesis.

• Kenneth A. Horowitz, Donald C. Lewis and Edgar L. Gasteiger, Plant "Primary Perception": Electrophysiological Unresponsiveness to Brine Shrimp Killing, Science New Series, Vol. 189, No. 4201 (Aug. 8, 1975), pp. 478-480, DOI: 10.2307/1740499

The authors tested Backster's hypothesis, by killing brine shrimp in the presence of philodenrons.

Test conditions conformed to those published by Backster or communicated in personal exchanges.

They found that

Inspection of the data and analysis by two statistical methods revealed no relationship between brine shrimp killing and electrical "responsiveness" of philodendron.

The Skeptics Dictionary gives more background, including a reference to another similar failed reproduction. They quote the author of that paper, Kmetz, as saying:

It is unfortunate that the popular press has taken Backster's experiments and presented the results to the public in such a way that many people now believe plants can do something that, in fact, they cannot. The press, for the most part, never mentions that articles on the Backster effect are based on observations of only seven plants. Perhaps they need to be reminded, again, that they are making exaggerated claims from an experiment that no one, including Backster, by his own refusal to do so, has been able to replicate.

Cecil Adams, of the Straight Dope makes some similar claims denying reproducibility, but offers no references to support his position.