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Are there any plants that are at least able to produce some sort of sound? Actively, I mean - depleting energy reserves to produce an audible output, preferably with no experimental amplification. Ultra- or infrasound is also ok.

Edit: I guess a different way of asking this is, "Are there any plant parts whose function is to produce sound?"

Zubo
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    I have heard anecdotally that you can hear the corn fields growing (at the peak time of growth). I am sure some of this is wind blowing but also the new growth rustling the drier outside leaves in thousands and thousands of plants. Bamboo I have heard the same thing about. – jbord39 Oct 07 '16 at 16:38
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    There are several plants, which, as a way of seed spreading, "explode", which will make an audible sound. Plants that do this are for example: lupine. – Ebbinghaus Oct 07 '16 at 17:11
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    These are good points, but the sound here is a byproduct - the plant "doesn't care" whether or not it is produced. I've edited to maybe make the question clearer. – Zubo Oct 08 '16 at 19:20
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    Do you mean, 'intentionally' produce sound? Intentional would be only for communication, right? – Polisetty Oct 09 '16 at 00:36
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    @Polisetty well, not necessarily - perhaps as a warning, or attracting something, or to generate vibrations for some other reason. Communication would entail a) also a listening apparatus and, more importantly, b) some way of actually interpreting the sound - some sort of neural system. – Zubo Oct 09 '16 at 20:49
  • @Zubo: I don't think a listening apparatus is necessary. After all, plants communicate with pollinators & seed dispersers by using odors and visual cues. I can't think of any fundamental reason they couldn't have evolved to use sound cues as well, though I don't know of an example. – jamesqf Feb 23 '17 at 19:45
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    It seems like Ritman and Milburn have done some work on acoustic emissions from plants. These two articles might be a starting point for you @Zubo : Acoustic Emissions from Plants: Ultrasonic and Audible Compared and Monitoring of Ultrasonic and Audible Emissions from Plants With or Without Vessels – Johnny Feb 24 '17 at 11:39
  • arthropods can probably hear plants hydrating, through their leg vibration sense. Sound is air displacement born of fast mechanical movement/diaphragms. few plants have mechanical movement. Sound has little use in defense, even insects don't use it, arthropods mostly use it for advertising their presence and strength and energy. investing in an auditory structure isn't economically and ecologically documented for a plant. – bandybabboon Sep 24 '18 at 06:40
  • not audible to us humans without some tweaking, but apparently plants do! https://www.cnet.com/news/listen-to-the-sound-of-plants-responding-to-the-world/ – Félix Gagnon-Grenier Jan 15 '22 at 19:41

2 Answers2

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Plants make noise all the time as they transport water but that is believed to be an unintentional by-effect. As to the possibility of plants intentionally making noise, my intuitive answer was no but I might well be wrong, there is actually increasing evidence that plants might produce vibrations for communication.

Two examples: Gagliano (2012) discovered that young maize roots subjected to a 220 Hz sound (check out the figure, not sure if I'm allowed to copy it here) grow towards the sound source and additionally emit periodic bursts of sound themselves for as of yet unclear reasons. Gagliano, Renton, et al. (2012) demonstrated that chili plant seedlings grow faster in the presence of an adult fennel plant even though this adult plant was isolated in a such a way that it could not communicate via any known mechanism (chemical, light) with the seedlings, indicating influence through an unknown mechanism. The authors consider both magnetism and sound as possible unknown communication methods.

I don't think any of these sounds would be audible for humans though.

Acoustic emission analysis and experiments with physical model systems
reveal a peculiar nature of the xylem tension. 
Laschimke, R., Burger, M., & Vallen, H. (2006).
Journal of plant physiology, 163(10), 996-1007.

Towards understanding plant bioacoustics
Gagliano, Monica et al.
Trends in Plant Science , Volume 17 , Issue 6 , 323 - 325

Out of Sight but Not out of Mind: Alternative Means of Communication in Plants.
Gagliano M, Renton M, Duvdevani N, Timmins M, Mancuso S (2012) 
PLoS ONE 7(5): e37382. doi:10.1371/journal.pone.0037382
Koen vd H
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This is a more anecdotal answer, and it may not be what you are looking for, but I had a couple of water-hungry leafy plants in the past (Cannabis spec) that would look something like this -

drooping
Source: Sensi Seeds

...Note that mine were a lot bigger. After watering them and leaving them in the sun (enhances re-hydration by promoting water flow through evaporation of water through the leaves) you could literally see the leaves and stem erecting themselves again by the re-hydration process. If I remember correctly, some of those leaves would make audible sounds when they became dis-entangled from underlying leaves (popping sounds). They would look something like this after watering them.

rise and shine source: AllBud

Note that these audible effects likely only happen in leafy, swift-growing (rapid metabolizing) plants like Cannabis.

AliceD
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