I'd like to make a sentient plant species that can perform tasks such as communication and problem solving.

My Definition of Sentience

When asking this question, I mean sentient as in able to rationalize and solve problems without solely relying on instinct. I believe there are two levels of sentience. The first is animal level sentience, which is basically where they are able to communicate and socialize on a low level and have simple emotions. The second is human level sentience. Our emotions, thoughts, and social lives are extremely complex compared to animal's. I am looking for the human level sentience in these plants.

What I Already Know

I know that technically speaking a plant is a life form that uses photosynthesis to produce food for itself in order to survive (though other life forms can do photosynthesis too). That's about it. I am not a botanist.

What I'd Like to Know

I'd like to know how this hypothetical species could fit my definition of sentience (I'd also like for them to be mobile, but it's not a must) while still technically being considered a plant. (please note: I am not wondering whether or how a plant could develop sentience, this question is more about whether a sentient plant is still a plant while being intelligent as a human)


It would be something like this:

Audrey 2

There are two issues you need to overcome with a plant like this. The first is the sentience quotient (SQ). SQ is a measure of how fast bits can be processed vs. the mass of their calculating organs, measured in bits/s/kg, and usually shown on a logarithmic scale. All neuron based life forms sit within a cluster around +13, including humans. Plants score a -2 while carnivorous plants like Audrey 2 rank at a +1. The first challenge would be overcoming the massive 10-orders-of-magnitude difference in processing rate.

The easy solution would be to let plants use neurons, but there's a price to pay. Neurons are not cheap to maintain. The human body dedicates 20% of its total power to the brain. This is where the limits of photosynthesis come in. It's not possible to generate enough power for such a brain using photosynthesis (I believe there was a past question on WorldBuilding regarding whether a human could live of photosynthesis alone, and the answer was "not even close").

Probably your best bet would be to abandon photosynthesis as a primary food mechanism, and instead have an immobile creature that feeds off prey animals. Perhaps it hypnotizes them into drawing too close. That would require a real brain to accomplish.

  • $\begingroup$ This is a very thorough answer, thank you. I just up voted it. But it still didn't address one issue: is a plant still a plant if it abandons photosynthesis altogether? Or are you saying this creature will still be able to use photosynthesis on a low scale, just as a minor way to obtain energy. $\endgroup$ Mar 14 '17 at 1:43
  • $\begingroup$ @BlippThePanda photosynthesis is not a requirement to be consider something a plant. In fact, there are instances of plants that lack the pigments for photosynthesis. For example the Monotropastrum humile. $\endgroup$
    – Theraot
    Mar 15 '17 at 5:42
  • $\begingroup$ @Theraot The page for that plant mentions that it uses a fungi for its energy, but I'm failing to understand what exactly that means. Do you know if that means it is fungi and not a plant? Or has a symbiotic relationship with fungi that grows on it maybe? $\endgroup$
    – Bazul
    Mar 16 '17 at 18:20
  • $\begingroup$ @Bazul it is a plant parasitic on fungi. This should help understand how it gets nutrients: Mycorrhizal fungi associated with Monotropastrum humile (Ericaceae) in central Japan. See also Myco-heterotrophy. $\endgroup$
    – Theraot
    Mar 16 '17 at 20:47

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