Plants channeling light into their roots?

Question

Without magic, is it possible for a plant to channel light (all colors) to/through its roots?

What I'm thinking is having a giant cavern with a bunch of these plants above. The roots go down and cover the ceiling of the cave. When the sky is blue the roots either turn blue and/or give off a blue light. If there are clouds in the sky they are seen in the cave. In a way that's like a camera on the surface and a screen on the roots. Or have the whole plant change color, like a chameleon, to show what is above.

Answer 1

Without magic, the easiest way to achieve this would be for the roots to contain chemiluminescent substances. The leaves absorb energy from the sun, and the roots convert that energy back to light.

There are a number of issues:

• It's slow - the roots would continue to glow long after the sky goes dark. They would continue to glow until the plant runs out of energy, unless there was some kind of signalling system, or a hormone released by the leaves that caused the roots to shut down.
• It's monochromatic. The glow of the roots is dependent on the chemicals, not on the colour of the light shining on the plant. There could be multiple chemicals.
• On a sunny day, most of the light comes from the sun (which is white, not blue). If you want to make a camera, you need a lens of some type. This can be gotten around -- you don't need one big lens, only little lenses on each tree, or even a pinhole lens. But then all the trees need to be pointing their cameras the same way.
• It's costly for the plant. What benefit does the tree get from having glowing roots? It must be pretty important, since generating light this way uses lots of energy, and plants don't have lots of spare energy. Perhaps the glowing roots attract insects, and the tree gets essential extra nutrients as a carnivorous plant (like an upside-down sundew)
• It's pretty dim, You can't read by the firefly light, The process of turning light into food, and food back into light is very inefficient (expect 99% wastage of energy in the process) This means the cave won't be lit up like the day.

There are real glowing mushrooms, and bioengineered plants that glow dimly. However the reality is a long way from a cave that reflects the sky.

The lens issue is the hardest to solve. That plants could have glowing roots is plausible. That a forest can cooperate to form a detailed image of the sky may require magic.

Answer 2

You could try something along the lines of a venus fly trap. Venus fly traps have modified leaves (the kind with "teeth" people often associate with the plant) when they can't get enough nutrients from the ground. When there's plenty of nutrients, those leaves don't even form.

As for your plants, you could have their roots capable of ensnaring prey and absorbing nutrients from said caught prey. The light, then, would act as a lure for prey. When there are plenty of nutrients in the ground, the roots would not have to dedicate energy to creating the chemicals needed to cause luminescence. But when nutrients are hard to come by, the lights go on!

Now, this would effect your ecosystem. You'd have to have life that would actually be caught by these plants. They can't have a system to catch prey if no prey exists. So, while you don't necessarily have to go into detail of creating a life form, you could briefly describe some "creature" being caught in the roots, obviously dead, looking as though drained. Or something like that, anyway.

Answer 3

Take a look at marine mammals

As discussed by the other answers, everything takes energy, so if this evolves, there must be a good reason. My solution is camouflage.

Many aquatic creatures have bright undersides and dark backs. This means that creatures looking up at them from below may mistake them as being part of the rest of the sunlight they see - or from above, they may blend in with the seafloor.

Perhaps your plants started out on the surface of a body of water, or in the treetops, or on ledges, and most predators were below them. It would be evolutionarily advantageous to change root color throughout the day because it would fool predators into thinking they weren't there - or were something else - etc.

Other answers are correct - these lights will have to be dim, and complicated processes must produce them that may not be efficient - but that is true for all solutions to your problem. This just justifies how your plants evolved.

Answer 4

You could have the plants costruct what would be, in essence, organic light guides.

Why would a plant evolve such a mechanism is a bit difficult to justify though. But the plants might have evolved to resist extremely hostile environments, where the "parent" plant in all likelihood dies and the "young" sprigs are kept safe underneath. The deeper they go, the safer they get, but of course they would get almost no light as soon as their shelter is more than a few millimeters deep.

Obviously most of the plants would have instead preferred to go the "deep hibernation" way.

Solutions such as transparent roots don't work very well, but said roots would have evolved to get hard, semitransparent excrescences similar to veins in order to safely bring light to the seeds in their bunkers, waiting for the conditions to be favourable once again. In time, these "crystal veins" would have become reasonably efficient light guides.

Something like this.