This is one of the more exotic takes on another Earth. One where somehow, someway, plants become sentient with at least one species becoming sapient.
Oh and none of them are green. Why? Because they can’t use photosynthesis. They had to give up leaves and roots. Let me explain.
Plants, unlike animals make use of propagation and hybridization even easier thanks to cutting, grafting, and intermediate growth. Probably among other things. While this doesn’t immediately make them new species, with enough time and populations they can become very unique. It’s why we’ve got corn.
So does that mean these sentient plants were cultivated by someone outside? Possible. I mean people are leaning into the idea that our ancestors were genetically modified from pre-historic apes.
But even that requires a lot of conditions, especially if you’re a plant. For one photosynthesis would have to be not so viable. An opaque atmosphere for example or other organisms outcompeting these plants for sunlight. Like trees that make a jungle too dense. Or fungus.
So instead of light, external digestion like carnivorous plants and nutrient absorbing surfaces on air plants is what keeps them going. This would make these plants sessile where they capture and digest organisms both animal and other plants.
A few of these plants would use clippings to grow into new bodies as well as self-grating to create bodies of multiple connected organisms. This formed a proto-nervous system where signals are shared across grafted tissue, memories form from nutrient trails and past pain to help in reconfiguring for survival. But without a centralized brain, these early plants would distribute intelligence across nodes while prioritizing chemical memory or electrical signaling across a web of tendrils. This allows plants to respond to environmental input with rudimentary decisions like retracting tendrils, close traps, or isolate dying parts.
To avoid repeated damage, learning which prey is the most nutritious, or growing toward or away from certain stimuli based on past outcomes, a proto-sentience was formed.
Which to use effectively, the plants started to develop rudimentary moods as an early-form of perception. Pressure sensitivity, chemical recognition, thermal gradients, and electric field sensing among others.
This gave the plants a distributed awareness more like fungal intelligence or slime-molds. Sentience fully capable of learning and adapting, capable of feeling something like pain/pleasure. But no sapience. At best, these plants have internal states that mimic desire, fear, and hunger. Yet had plenty of species emerge. Some even have cooperative colonies.
So how can it go a step further? Convergent evolution with animals. Again, whether natural or not, this requires a highly competitive, shaded environment. Since photosynthesis can’t be what gets these plants going, they need an abundant access to prey, carrion, or decomposing material. But more importantly, there needs to be a long———evolutionary pressure to more responsive, mobile, or behaviorally flexible.
Where’s the best environment for this? Dense-shaded jungles, wetlands, and cavern ecosystems.
Such factors would at least allow carnivorous plant digestive glands to evolve into internal organs. Like stomachs and livers, maybe even multiple digestive sacs. But unlike cows or tough veggie eaters, they would isolate prey and allow selective absorption. Maybe some rudimentary muscles to constrict prey and manage digestion. Just wonder if they get as many cramps or constipations.
Respiration like with algae meanwhile would have to shift to thin tissues or pores. Maybe even internalized high surface area for gas exchange like in alveoli. Might even use water flow or air currents to passively enhance respiration.
On the other hand, since these plants wouldn’t have roots or leaves, they’d have to use flora’s other vibration sensors. The whorls that make flowers! Not just the responsive petals, but centralized structures that evolve into resonators and the internal pressure chambers/vibration detecting tissues could mimic the cochlea… The inner ear! Funnily enough even that spirals.
As for the petals (or petal-like structures) they have new functions to enhance hearing. Effectively, the petals act like the outer ear of mammals, external sound collectors that direct vibrations toward the inner resonance chambers. They also have secondary functions like protection for the delicate hearing organs and play a role in their communication system. Both amplifying and modulating the sounds they produce.
Next vision through eye-like stalks. Since stems already have specialized photoreceptive cells, they can become eye-like organs. It’s just that they need to start as cup-shaped light sensitive pits. With enough generations, one or more lines would gain pigmented lenses or transparent cell layers to focus light. Plus stalks are useful for elevation.