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Is it possible for a plant to have the ability to fly?

More exactly, the plant would either need to live without having any roots (and it would never need to touch the ground), or with the ability to re-root itself in another location from time to time, or maybe a plant that has a permanent pedestal/base that it could detach itself from to avoid a predator or to hunt like a carnivorous plant. The plant would also need to ability to control its altitude, and keep it from floating higher and higher (or if it needs to re-root, to be able to come back down from the air).

The setting does not have to be on Earth but it must be able to support life. Bonus point if it's possible on an Earth-like planet.

Examples:

  • Deku scrubs The Business scrub is a plant that can fly with the propeller on its head.
  • Peahat Has a base it can return to after hunting. The propeller is under the plant. I suspect that neither of these two plants can fly for very long.
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    $\begingroup$ The distinction between "plants" and "animals" is entirely set by a coincidence of evolution. Alien life forms would likely not have such a distinction, or the distinction may be much more nuanced. For example, "plant" functions may be specialized cells, much in the same way that we have specialized cells, and "plants" contain more of these cells, while "animals" contain less of these cells. $\endgroup$ – Nick2253 Mar 2 '15 at 18:13
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    $\begingroup$ As far as not having roots, epiphytes are like that (eg, Spanish Moss) $\endgroup$ – Nathan Long Mar 2 '15 at 19:05
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    $\begingroup$ Would it be acceptable to have plants that only fly for short bursts at a time, like only when it's windy? $\endgroup$ – Mooing Duck Mar 2 '15 at 20:00
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    $\begingroup$ At what point is this no longer a "mobile plant" and really a "strange, slow animal without traditional senses?" (many animals night be lacking in one or more senses) Is the critical distinction photosynthesis (plankton cross this line)? Willful action (monera)? some sort of nervous system (jellyfish)? What is making this a plant? $\endgroup$ – Isaac Kotlicky Mar 3 '15 at 5:31
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    $\begingroup$ Aren't flying plants known as seeds and spores? $\endgroup$ – reinierpost Mar 3 '15 at 10:44

13 Answers 13

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It's more likely there could exist a plant which has a flying phase of its life-cycle.

Image of green floaters

Does it really fly?

It might be more appropriate to call it floating, since the energy required for what is more traditionally thought of as flying, would be too much for a plant. Blimp plants/animals have long been imagined in science fiction, called living gasbags. It's also an interesting idea about alien life on planets with low gravity or thick atmospheres.

The plants will use hydrogen, not helium

Despite the relative safety of using helium as a lifting gas, at least for Earth, it's very unlikely a plant could extract much helium from the atmosphere to thrive. Besides, helium is a noble gas, it's the least reactive element. There isn't a chemical process that any plant can use to collect it.

Far more likely, the plant would use hydrogen gas. It would give slightly more lift and the plant already produces it during photosynthesis. Someone is going to cite the Hindenburg and claim plants would suffer the same fate, that's very unlikely, the plant would simply be a bit more flammable. It's like pointing to a forest fire and saying clearly plants wouldn't make themselves out of flammable materials if they want to survive.

What does it eat?

If it's a carnivorous plant, it's more likely to be something like a jellyfish floating in the air. Capturing unaware birds and insects. There is a version of these carnivore-hydrogen-gas-bag in Shards of Honor by Lois McMaster Bujold.

Image of a floating jellyfish

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    $\begingroup$ Agree on the floating versus flying point. I can see floating and utilizing wind currents to move about. $\endgroup$ – James Mar 2 '15 at 21:38
  • $\begingroup$ Are there better lifting gases than hydrogen? Alkanes + greenhouse effect seems a more natural product of biological processes than hydrogen $\endgroup$ – Jesvin Jose Mar 3 '15 at 7:54
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    $\begingroup$ @aitchnyu In gas phase N atoms/molecules of gas take up the same space. So the mass of an atom/molecule is what determines the mass of a litre of gas (unlike in a solid where density also plays a part). You're going to struggle to find something lighter than the lightest element on the periodic table $\endgroup$ – Richard Tingle Mar 3 '15 at 13:30
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    $\begingroup$ @aitchnyu lighter than air, but not lighter than hydrogen. It is a lifting gas, but not a better lifting gas (at least not from the point of view of mass lifted) $\endgroup$ – Richard Tingle Mar 3 '15 at 14:09
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    $\begingroup$ The issue would be how to keep the H2 sealed in an organic structure (we have trouble storing it in gas form). And, more than for hunting, the mechanism sounds ideal for spreading seeds (less weight to carry, more benefits for the species). Any way, good answer, +1. $\endgroup$ – SJuan76 Mar 4 '15 at 2:28
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Well, it all depends! :)

There are tumbleweeds which grow, produce seeds, then die, break off and the whole plant moves by the wind, depositing its seeds in different ways, it's sort of like flying.

Of course seeds fly all the time, dandelions and other similar flowers, Maples have their little helicopters.

However, for plants to fly, first they need help. It is unlikely they are going to flap leaves and take off. So they will most likely be dependent on the wind.

One thing that could work would be parachute/umbrella type features that can carry the plant away, or at least enough of it to continue surviving when it lands. This could be a cross between a tumble weed and say a Jade plant. You can break off a piece stick it in the dirt and it will root and become a new and separate plant.

Otherwise maybe you have a steppe where there is always a lot of wind, and a plant that is threatened (by animals or drought) could clip its roots and catch the prevailing winds to move, it could open and close its umbrella/wings like petals on a flower and so fall back to earth to try rerooting.

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    $\begingroup$ every time I try and write an answer, you've got one concisely summarizing everything I would have said. Thanks for reminding me it's maples with the helicopter seeds, though, I couldn't think of which tree did that. $\endgroup$ – DaaaahWhoosh Mar 2 '15 at 17:58
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    $\begingroup$ @DaaaahWhoosh I'm saving you all that work! ;) $\endgroup$ – bowlturner Mar 2 '15 at 18:00
  • $\begingroup$ Why can't plant just have a flapping wings like birds? Cadaverous plans known to be able to move its jaws pretty fast. $\endgroup$ – Ivan Balashov Mar 2 '15 at 23:24
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    $\begingroup$ Buzz: This isn't flying, this is falling with style! $\endgroup$ – Samuel Mar 2 '15 at 23:34
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    $\begingroup$ @IvanBalashov Flapping flight requires a lot of energy, plant metabolisms don't really support it. $\endgroup$ – Tim B Mar 3 '15 at 10:05
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One example of such a thing would be an airship-plant

So I will start with the biggest problem: which gas should it use?

  • Hydrogen: On Earth, Hydrogen is rare in the atmosphere, but a plant may be to extract it from water.
  • Helium: Helium is also rare on Earth, and it doesn't react with anything. That means that in order for Helium to work is in an atmosphere that is richer in Helium than ours. That shouldn't pose a problem to the general chemistry of the atmosphere. To refine Helium, a plant basically has to take a big gulp of air, and then kick everything that is not Helium out. That can be done thanks to a semi-permeable membrane (which is used IRL), or thanks to any chemical process you like. However such a big concentration of Helium is unlikely, because it would tend to escape the atmosphere [and it may accumulate in the upper atmosphere, and not at ground level]. I can see two things that would try to mitigate this:
    • a colder planet, where Helium would have less kinetic energy to escape from gravity,
    • a planet further away from the sun, where solar wind wouldn't be as strong.
  • methane could be used.
  • finally, there is also the possibility to use hot air, heated either thanks to some sort of lenses, or thanks to a chemical process.

All in all this seems rather complicated on an earth-like planet, but it could work better on an analogue of Titan: there, the atmosphere is made of 98,4% nitrogen, 1,4% methane (up to 4,9% at surface level) and 0,2% hydrogen, making light gases readily available.

Reproduction Well pollination still works :) You have to be careful that seeds do not though. However one could imagine that instead of a fruit, plants produce an already-formed baby-plant together with its balloon. Sort of like a stolon, which would then break when the new plant is mature-enough.

Water Depending on the climate, those plants could harvest water directly from the atmosphere, or they could stock it when it is raining.

Nutrients Plants heavily depend on soil in order to get nutrients. But a flying plant would have to carry it with itself. A good way to do that would be to use bird poop. Birds would have a huge advantage by living on your plant: they are free from many predators. The plant could also lure them by producing fruits or something like that.

What would it look like? Your plant has to stock water, nutrients and helium. How can all that fit? The problem is that you can't put much on top of a balloon, or the balloon will quickly become unbalanced.

One solution could be to have a torus-shaped balloon. With roots forming a cone beneath it. The cone could be where water is kept, and the roots would form a good place for birds to make their nests. The good point is also that it means that the top of the balloon is free for the plant to grow leaves to do photosynthesis.

-- optional idea --

Rather than birds (or on top of it) your plant could use insects. The good thing is that insects are small enough that even a small plant could use them. Moreover you can imagine huge millennium-old-plants pushed by the winds, and that travel together with a swarm of insects, which would leave a trail of devastation on its way.

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  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$ – a CVn Mar 5 '15 at 10:16
  • $\begingroup$ Alternative source of Helium- nuclear decay. That is the reason that our atmosphere still has Helium. Just need to accumulate it from underground sources such as bubbling through petroleum leaking all the time. Some other gases come through the petroleum such as carbon dioxide and hydrogen sulphide but a lot easier than removing Nitrogen and other components from the air. Cracking of petroleum to produce hydrogen is probably even easier than getting it from water- just a suitable enzyme needed. $\endgroup$ – user2617804 Apr 3 '15 at 11:15
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If you are imagining plants that spend their entire lifecycle in the air, the genus Tillandsia would make a good template. Tillandsia do not "fly" but grow without soil and collect the nutriets they need from the air (e.g. dust, dead insects, leaves) through special structures in their leaves.

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No. Plants are optimized for life which does not require movement.

It makes sense that eukaryote cells are split to plants and animals (and fungi, and more but anyway). Life requires optimization and compromises. Once you start optimizing for one feature, other competing features lower your lifeform fitness in your selected niche.

Plants are optimized for life life which can be powered by photosynthesis — and this question/answer about green men explains why the amount of energy available from photosynthesis is not enough to power kind of active life which animals do - and flying is rather extreme in that sense.

Plants deal with the meager energy input from photosynthesis by NOT spending energy to move, and have rigid cells walls (unlike animals) so they don't need even energy to stand still. But they do capture sun energy and provide sustenance for everything else on Earth (roughly).

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  • $\begingroup$ On the other hand flying/floating seeds are not uncommon since plants gain a lot from spreading their seeds widely. Coconuts are found across the globe because they float well in water. I could imagine something like hydrogen filled seed pods that burst under conditions that imply usable ground bellow. $\endgroup$ – Murphy Mar 3 '15 at 11:53
  • $\begingroup$ Seeds are not plants. Seeds are designed and optimized to spread. Plants are designed to stay put. $\endgroup$ – Peter M. Mar 3 '15 at 15:06
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    $\begingroup$ Aren't plants just a temporary body created by seeds to reproduce themselves? Like chickens ;-) $\endgroup$ – Steve Jessop Mar 4 '15 at 2:49
  • $\begingroup$ Yes, and cells are just a way how gene makes copies of itself $\endgroup$ – Peter M. Jul 2 '15 at 17:59
  • $\begingroup$ Interesting. You might get autotrophic multicellular life that flys but be different enough from plants to be classified as an entirely different thing. $\endgroup$ – JDługosz Jan 14 '16 at 6:17
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Larry Niven postulated Stage Trees, trees with a solid-fuel rocket as the trunk. I guess interplanetary travel counts as flying. :-) In addition, in the Smoke Ring (not a planet, but a habitable earth-like gas torus), everything, including plants, needs to be able to fly, including the massive Integral Trees.

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    $\begingroup$ If I recall correctly, the Stage Trees were engineered rather than natural. When I first read that, I thought "silly", but now I wonder if it might really be possible in the foreseeable future. Certainly raises the question whether the OP considers artificial "plants" in scope. $\endgroup$ – Keith Mar 2 '15 at 23:51
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Silk flight

If flight does not need to be sudden or often, the method that spiderlings use to fly may be plausible for a plant. Simply producing silk (or a similar strong, lightweight liquid solidified by tension) will allow a thread to build up pulled by the wind, until it is long enough that the wind lifts the plant into the air. A number of such silk glands at different positions on the plant would reduce the required length (and hence the required open space for lift off).

This approach requires only that the plant be able to produce a suitable liquid for thread formation. The rate of production can be low, with the thread slowly extending over a period of days or weeks before sufficient lift is achieved.

Initiation

Although the wind provides the required tension once the thread gets going, a small amount of tension is required at the start in order to get the thread going. Spiders can use their legs to pull the thread out until it is long enough to release to the wind, but moving parts are very expensive for a plant. A less resource-intensive approach would be to start the thread with a weight to pull it downwards.

When the silk gland is mature, the tip of it is dislodged by the surrounding tissue drying out, and as it falls it pulls the silk liquid taut, turning it into solid thread. The weight is heavy enough to pull out new thread, but light enough to be caught by the wind to continue the thread growth rather than reaching the ground and stopping. The shape of the weight can be wide and flat and possibly feathered, to make it catch the wind despite being heavy.

Once the thread is long enough to reach further up from the ground where the wind is stronger, the strength of the wind breaks off the weight and the thread flies without further need for it. This keeps the thread light and reduces the length required for lift off.

Evolutionary path

Since this arrangement only gives rise to flight when complete, another reason is required for the evolution of silk glands and feathered weights.

For example, the silk may have first developed as a sticky liquid to trap insects (either as prey or simply to kill pests and parasites). Alternatively it could have been used to attach seeds to passing animals that brush against the plant. Over time the silk glands increased in size and allowed longer lengths of thread to be produced. The selective pressure causing this may have been that seeds hanging from longer threads attached to passing animals were more likely to get caught on vegetation and removed above ground, rather than in the animal's cave or burrow where there is no light. Being removed earlier would also be an advantage if some animals are inclined to eat the seeds during grooming. If the threads were used to trap pests and parasites, a selective pressure may have been that a longer thread meant that the struggling insects moved around more, attracting natural predators that would help keep the plant free of pests. Either way, the threads produced eventually become long enough to catch the wind, and then selection can act on that.

The feathering of the weight to allow catching the wind could then feasibly develop without alternative explanation, but it may already have started in the form of mimicking the insect pests in order to lure them to the silk glands. This would mean that no insect is required in order to start the thread. In evolutionary history it may have been insects that dislodged the weight and triggered the thread production, but eventually the weight could be released independently, giving finer control over the timing (and making it more likely to happen during high winds).

As an intermediary stage, they may be plants that form threads not long enough for flight, but long enough to entangle in animal fur/feathers so the whole plant can hitch a ride that way (probably only for short distances while the disgruntled animal makes efforts to dislodge it). Over many generations the thread becomes long enough to catch the wind and preclude the need for an animal.

Size and weight

Spiderlings are very small. Similarly, silk flying plants would be limited in size. In an Earth-like setting, these would likely be tiny - perhaps like mosses that do not need permanent roots and can colonise places beyond reach of most other plants. If you wanted larger plants (perhaps "kite trees"), then you would need a much denser atmosphere.

If you imagine a branching evolutionary tree, then even an Earth-like setting could have larger silk plants, but only the smaller species would be capable of flight. So then you could have kite trees with long threads trailing off into the sky, serving some other purpose like those described above. Their tiny relatives would produce far fewer strands but would take flight whenever the wind picked up, unlike their huge deep rooted cousins.

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That Peahat looks like this swimming anemone, and anemones are half plant:

Sea anemones are classified as being animals, but two new genetic studies have found that these water-dwelling creatures are technically half plant and half animal.

Anemone swimming away from unfazed sea star

Depending on densities, similar beings could fly on alien planets, harvesting nutrients from sky and soil, and perhaps even hunting other organisms by smell.

Earth also has self-propelling plants, albeit in spore form:

Before this study, it was not clear what the function of the [horsetail (Equisetum)] spores' leg structures was.

"People assumed they were like wings, so they would help dispersal into the wind," explained Dr Marmottant, "but here we show they actually induce motion on the ground."

"And more importantly, they also enable jumps, which means [the spores] can enter the wind currents. And once you're in the wind current, you can travel long distances, which is an evolutionary advantage, because it means you can disperse your [spores] very widely."

Horsetail (Equisetum) spore jumping into the air

These features appear to have been combined in Emrakul, the astral abomination: enter image description here

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A problem with your question is the definition of "plant" (see Wikipedia).

If you use something like "rigid cell walls and photosynthesis" as your definition, the plant might have some sort of sensory organs and limbs like the Venus Flytrap (see Wikipedia). Real plants don't have enough energy to flap their wings and fly away, but a fictional plant might do it.

Another idea would be a plant which generates hydrogen to fly like a gas balloon.

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Yes it is quite possible. Look further for details "Buckminster Fuller"s Cloud Nine. Geodesic spherical cities floated by only a few degrees hotter air inside their sphere.

It works in any gas mixes or atmospheres. It works even in pure hydrogen atmosphere (you can fly hot hydrogen balloon inside it)...

In sphere, area increase by power of 2 but the volume increase power of 3. There is no matter how heavy or how large the plant is. It can always cover enough volume to float itself.

Larger is better, because you need less temperature difference to produce enough lift to float.

So you only need massive spherical plants, structural integrity and a way of keep their inside warmer than their outside in any atmosphere.

Like drifting sargassum or stationary coral reefs, they can host whole habitat / ecosystem of their own (symbiotic,parasitic, etc...).

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You could have plants that fly instead of float. Something like a biological spring that winds up, and when the plant has produced enough seeds and such the root releases and the spring unwinds spinning some kind of propeller like a Deku. The flight would be short, but one interesting use would be as a kind of land mine. While it's flying and spinning it's also spraying seeds like bullets in all directions.

There are earth plants that can move rapidly, but if you want something that can hunt it has to have some amount of intelligence. Things like venus fly traps move quickly when their trigger hairs are twitched, but they react to outward stimuli, not intelligently.
http://news.nationalgeographic.com/news/2005/05/0526_050526_extremeplants.html

You could have some kind of plant/animal hybrid with different life cycles. Grows from a seed, stays rooted until it's animal level intelligence matures, then flies for short bursts looking for prey. when it makes a kill it takes nourishment from the fluids and plants seeds in the corpse to grow new plants. It could even hunt with the seeds, firing the seeds at prey. The mistletoe plant does something similar to spread it's seeds from tree to tree. Other plants have similar mechinisms:
http://www.virtualherbarium.org/GardenViews/GoingBallistic.html

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Yes, but why would it? The question isn't so much could a plant fly as many plants do at some stage (usually as seeds) or even how could a plant fly as there are any number of ideas about that, personally I like the hydrogen gas method. But what evolutionary situation would make it profitable for a plant to leave behind the abundant nutrients and water of the soil for the sterile and arid sky? I'd suggest that if you want flying plants the sky has to be a rich and rewarding environment, have a look at Larry Niven's The Integral Trees and The Smoke Ring for some ideas about plant life in the endless sky of a gas torus. As for flying plants on an Earth like world you could see that if there was enough ground predation to make the sky the safer option and there were enough resources to survive in the air, a slightly thicker wetter atmosphere would help there. The thing I would expect to see the most would be plants where part takes off when threatened, fly only a short distance, and settle again, a bit like a skink shedding it's tail to escape a predator.

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Just as an another point of view: did you take a look at https://en.wikipedia.org/wiki/Aeroplankton? It contains moses, bacteria, liverworts, viruses. Same principle as with regular planctons does apply.

In short: Plants small enough to drift in the wind is one way to go.

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