Sentience in Plants: A Green Red Herring?

The attribution of sentience or consciousness to plants is currently a topic of debate among biologists and philosophers. The claim that plants are conscious is based on three arguments: (i) plants, like all living organisms, are sentient (biopsychism); (ii) there is a strong analogy between the phloem transport system of plants and the nervous system of animals; and (iii) plants are the cognitive equals of sentient animals. On the basis of a model of consciousness that spells out criteria for assigning sentience to a living organism and presents a diagnostic evolutionary marker of consciousness, we argue that these arguments are flawed and discuss some of the ethical issues they raise.