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Hypothesis On Electrostatic Seed Dispersal Strategy


Acme
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I have formed an hypothesis that this particular plant has evolved the strategy of widely dispersing its seed using electrostatic force. Having made several efforts to find some reference to such a strategy and finding none, I thought I'd put the issue to the forum audeience.

 

So, the plant is Western Yellow Oxalis - Oxalis suksdorfii. [aka Suksdorf Wood-sorrel, Western Yellow Wood-sorrel] Plants appeared as volunteers in my yard a few years back and I subsequently ID'd it & found it is ranked Sensitive in Washington State. In retrospect I suspect it hitched a ride home from one of my tramps in the wild.

 

Among its interesting qualities, the leaves fold when touched, the seed capsules burst explosively, and the leaves/stems are edible. Anyway, while sorting some seeds from their chaff with a bit of cardstock I noticed a fair number of the seeds clinging to the little piece of paper. Some nudging/bumping/brushing was required to dislodge the seeds and with subsequent sorting they would again cling to the cardstock.

 

As there were no aparent hooks, glue, or other reason for the seeds to cling I came to the idea it was electrostatic charge holding them. The seed capsules will burst on their own as they age, but at a certain stage of ripeness they will also burst when physically disturbed. My hypothesis is that when an animal disturbs the ripe capsules they burst, and the seeds fly out to cling to the animal's skin/fur/feathers and hitch a ride until the charge is lost whereupon the seeds drop.

 

So. Thoughts? References to this or other plants with this habit? I am posting photos of the whole plant, a bloom, the capsule, the seeds, and a link to a short video of a capsule exploding.

 

Thanks,

Acme

 

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http://www.flickr.com/photos/114331103@N07/13227029323/

Edited by Acme
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My yard is full of that stuff or something very similar, I'll have to see if the seeds do the same thing. I don't see any reason electrostatic forces couldn't be a factor, spores of ferns and or fungus might be a better model for electrostatic attraction since they are so much smaller.

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My yard is full of that stuff or something very similar, I'll have to see if the seeds do the same thing. I don't see any reason electrostatic forces couldn't be a factor, spores of ferns and or fungus might be a better model for electrostatic attraction since they are so much smaller.

You likely have Common Yellow Oxalis - Oxalis stricta back there. Could be native to N.C. but O. stricta is definitely an introduced weed here. I have not let any get to the seed stage as I pull them out whenever I see them, but a pic at the Wiki page shows similar capsules. >> http://en.wikipedia.org/wiki/Oxalis_stricta

 

I'm hesitant to attribute the apparent electrostatic action to simply size, as I have sorted many similar sized and smaller sized seeds without seeing the same effect. (California Poppy comes to mind.) I'm inclined to think the ribbed/ridged seed coat is a contributing factor to the [apparent] electrostatic action.

 

I have moved from the yard I found the plants in and I'm currently propagating the seeds I collected. I may have planted them all, but if not I'll see if I can reproduce the effect of the seeds clinging to the paper and make a video of it.

 

Thanks for the interest and input! :)

Do you have a magnification function on your camera?

The digital camera I took the seed shot with does allow a very close focus, within 1/8" of the lens as well as a 20x non-digital lens-zoom function. Problem with getting subject so close to lens is getting light onto the front of the subject. I also have a film SLR I just started using again and for it I have a 28mm lens as well as a 4x filter which I can try using for a closer shot.

 

Will try some closer shots and report back. :)

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Yeah, I've found a good bit about seeds clinging in general(mostly in farming applications) and electroculture(which I suspect is largely unrelated). Nothing about research into plants deliberately utilizing static electricity for seed dispersal, don't see any reason why it wouldn't be possible though.

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You likely have Common Yellow Oxalis - Oxalis stricta back there. Could be native to N.C. but O. stricta is definitely an introduced weed here. I have not let any get to the seed stage as I pull them out whenever I see them, but a pic at the Wiki page shows similar capsules. >> http://en.wikipedia.org/wiki/Oxalis_stricta

 

I'm hesitant to attribute the apparent electrostatic action to simply size, as I have sorted many similar sized and smaller sized seeds without seeing the same effect. (California Poppy comes to mind.) I'm inclined to think the ribbed/ridged seed coat is a contributing factor to the [apparent] electrostatic action.

 

I have moved from the yard I found the plants in and I'm currently propagating the seeds I collected. I may have planted them all, but if not I'll see if I can reproduce the effect of the seeds clinging to the paper and make a video of it.

 

Thanks for the interest and input! :)

 

The digital camera I took the seed shot with does allow a very close focus, within 1/8" of the lens as well as a 20x non-digital lens-zoom function. Problem with getting subject so close to lens is getting light onto the front of the subject. I also have a film SLR I just started using again and for it I have a 28mm lens as well as a 4x filter which I can try using for a closer shot.

 

Will try some closer shots and report back. :)

 

 

I'm almost certain the blooms on the ones here are purple but they are not in bloom yet and i'll take some photos when they are...

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Yeah, I've found a good bit about seeds clinging in general(mostly in farming applications) and electroculture(which I suspect is largely unrelated). Nothing about research into plants deliberately utilizing static electricity for seed dispersal, don't see any reason why it wouldn't be possible though.

Sounds similar to my search results in regards to the farm business.

I'm almost certain the blooms on the ones here are purple but they are not in bloom yet and i'll take some photos when they are...

Roger that...

 

So I got a few seeds to cling briefly to a cardstock slip and attaching video. As the film SLR images would be weeks away at best I borrowed the eyepiece projection technique from astrophotography and took some seed shots through my loupe. Depth of field issues made for a little blurriness, but it's better than what I had before. (Won't bore you with too much photo talk. ;) ) First shot is with CFL illumination only and second one with CFL and some added LED from a penlight. Seeds on average measure ~1mm across short axis.

 

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(Sorry; can't seem to figure out how to embed the player. D'oh! )

video: >> http://www.flickr.com/photos/114331103@N07/13233281624/

Edited by Acme
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The one that grow in my yard could be a cultivar, my yard is very wet, this area used to be a wetland, lots of odd flowers growing here and there, I may have confused the blooms. I don't try to suppress the native plants beyond an occasional mowing, I am one of those odd people who appreciate native plants and our wetlands are home to some unusual species...

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Just a thought, but could you try neutralizing their charge or maybe using a humidifier?

 

Be interesting to hear how it goes.

For the short video I made, the seeds may have been largely charge-neutral; only 3 ever clung to the paper slip after several minutes stirring them about. For that experiment the seeds were laying on/in a [red] plastic lid from a yogurt container. Humidity in the room was ~60%. (I have a hygrometer on the wall.)

 

I'm planning some more experimenting and I invite more suggestions. At first opportunity I'm going to find a small balloon and blow it up, rub it on a wool sock, and bring it near the seeds.

 

One other comment regarding the video with the paper slip. Of the 3 seeds that clung to the slip, all were aligned in the same orientation and their ribs were parallel to 'down'. If the ribs were acting as hooks I would expect them to be perpendicular to 'down'. I see this as a supporting ( ;) ) argument for the electrostatic explanation.

 

The one that grow in my yard could be a cultivar, my yard is very wet, this area used to be a wetland, lots of odd flowers growing here and there, I may have confused the blooms. I don't try to suppress the native plants beyond an occasional mowing, I am one of those odd people who appreciate native plants and our wetlands are home to some unusual species...

There are many hundreds of species in the genus Oxalis and pinks/purples are not uncommon even in wild species. When your yard buddies emerge I will help direct you to probe their oxalisnessesses so we may get to the bottom of things. :0

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I found a page or two on The Role of Electrostatic Forces In Pollination which you might glean clues from. Scroll up a bit to the title to read it all in the link..

Muchas gracias! Already I find some support from your source for an earlier proposition of mine.

I'm inclined to think the ribbed/ridged seed coat is a contributing factor to the [apparent] electrostatic action.

...In electrostatic charging, electrons remain relatively stationary and are spread on the surface of the object and concentrated on sharp edges. ...

Off to read more...

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I found out that R.Squarrosum uses electrostatics to throw seeds from itself.

 

 

The oval seeds of R. squarrosum have a strong electrostatic charge and ‘jump' to about 10 cm when manually extracted from the pockets. The function of the seed pocket is unknown, but it may perform a role in dispersal, for example by ants. http://www.plantzafrica.com/plantqrs/rhigiosquarrosum.htm

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I found out that R.Squarrosum uses electrostatics to throw seeds from itself.

Interesting. The seeds appear smooth in the photo, though I may see some small bumps/sharp points. Nonetheless while sharp points may concentrate a charge, they aren't requisite to carry one. Then the phrase "when manually extracted from the pockets" is a bit ambiguous as it implies human separation. ? However, I can imagine the seed 'jump' as a survival strategy for the plant if an animal attempts to eat the seed only to have it shoot off some distance.

 

When I do my balloon experiment I'll try some other seeds too, such as the California Poppies I mentioned.

 

Back to the electrostatic pollen paper, I found more of interest. (Note: I transcribed these passages and any grammatical errors may be my typos.)To whit:

... Normally plants possess small negative surface charges under clear fair-day conditions, and are, therefore, surrounded by electric fields of low intensity (Maw 1962). Under unstable weather conditions, as on a cloudy day or rainy day, the electric fields can change their polarity and the surface charges become positive. (Warnke 1977) The magnitude of the electric fields depends in part on the chemical composition of the plant, its height and the environment (Erickson and Buchamann 1983). The distribution

of the electric field around the plant varies with its shape, and the plant's electrical fields should be greatest near sharp points such as plant terminals including flowers (Dai and Law 1995). ...

So a negative charge 'usually' on plants. And again with the sharp points and perhaps the sharp point of the O. suksdorfii seed capsule plays a role in charging the seeds? Then too the bursting may play a role in charging the seeds? Oh for a high speed camera!! As it was, it took a 5 hour recording to wait for and capture the micro-second burst that I managed. Then too, what of the chemical makeup of the seed-coat? The ridges do have a different color than the furrows, so perhaps they differ chemically in a way that carries a charge better?

 

Now more from the pollen paper...

... Foraging bees usually possess electrically positive surface charges (Erickson 1975. Yes'kov and Sapozhnikov 1976, Wanke 1977, Schwartz 1991, Gan-More et al 1995). When a bee flies through the air it is confronted with electrical currents and its body will be electrostatically charged with "frictional electricity" (Warnke 1977). Warnke (1977) and Thorp (1979) suggested that in the case of pollen-seeking insects, accumulation of pollen on the surfaces of insects and pollen distribution by the insects are enhanced by the forces of attraction between the insect's positively charged body surface and the generally negatively charged plant with its pollen. ...

Not sure if other animals such as birds, mammals, or reptiles also collect a positive charge as they move, but if they do then the electrostatic setup I'm proposing is supported.

 

Off to do more reading... :)

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Interesting. The seeds appear smooth in the photo, though I may see some small bumps/sharp points. Nonetheless while sharp points may concentrate a charge, they aren't requisite to carry one. Then the phrase "when manually extracted from the pockets" is a bit ambiguous as it implies human separation. ? However, I can imagine the seed 'jump' as a survival strategy for the plant if an animal attempts to eat the seed only to have it shoot off some distance.

 

 

Maybe the surrounding material carries the requisite 'points' ...note that the action of the charge in this plant is a repulsive effect used for dispersion rather than an attractive one as in your test plant. It's a different but relevant use of electrostatics I think.

Edited by StringJunky
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!

Moderator Note

vampares,

 

This is not the first time that staff have had to remove your posts for being wildly off-topic and / or complete nonsense. Please stick to the topic outlined in the OP in future or staff will be forced to take further action. In the mean-time, I am moving your post to the trash.

 

Respond to this modnote via the report function or PM.

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Maybe the surrounding material carries the requisite 'points' ...note that the action of the charge in this plant is a repulsive effect used for dispersion rather than an attractive one as in your test plant. It's a different but relevant use of electrostatics I think.

Maybe. I would have to see more documentation than supplied in that article. Relevant or not, I agree that your example is different than the plant I'm discussing & while I appreciate your effort I see no practical use for my investigations.

 

I seem to be currently balloon deficient and so haven't performed any experiments. However, as I was unsure what charge the wool-rubbed balloon would carry I did some reading and found it would be positive. Also found that if I rubbed leather on the wool it would acquire a negative charge, so I'll be trying both. Also of help in this area was a Wiki article on 'triboelectric effect'. >> http://en.wikipedia.org/wiki/Triboelectric_effect

 

At last check there were no views of the video I linked to of a pod exploding. :( It might be helpful to have a look in order to form an opinion on my suggestion that the explosion event may be responsible for imparting a charge to the seeds. Just sayin'. :)

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This happens all the time with small seeds. After years of handling Arabidopsis, I can say they often stick to paper. I find it really far-fetched to think this evolved rather than simply the fact that they are small and so such forces under right circumstances could have an effect.

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This happens all the time with small seeds. After years of handling Arabidopsis, I can say they often stick to paper. I find it really far-fetched to think this evolved rather than simply the fact that they are small and so such forces under right circumstances could have an effect.

Perhaps you could elaborate on 'far-fetched'.

 

As to Arabidopsis, I handle them a lot too when I pull the introduced ones such as Thalecress as weeds.I haven't handled them with paper, but I don't find it surprising that other plants than O. suksdorfii may take advantage of electrostatics for seed dispersal.

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Perhaps you could elaborate on 'far-fetched'.

 

As to Arabidopsis, I handle them a lot too when I pull the introduced ones such as Thalecress as weeds.I haven't handled them with paper, but I don't find it surprising that other plants than O. suksdorfii may take advantage of electrostatics for seed dispersal.

 

Often times when you are doing stuff like this, such as handling with paper, you are creating a very artificial situation. Paper tends to have lots of electrostatic charge. I've had it stick to me before...does that indicate that I evolved to have some sort of electrostatic interaction? I find it highly unlikely that under real-life conditions...changing temperatures, moisture, etc, etc that this will be a factor.

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Often times when you are doing stuff like this, such as handling with paper, you are creating a very artificial situation. Paper tends to have lots of electrostatic charge. I've had it stick to me before...does that indicate that I evolved to have some sort of electrostatic interaction? I find it highly unlikely that under real-life conditions...changing temperatures, moisture, etc, etc that this will be a factor.

Mmmmm... I find your assessment rather lacking in scientific curiosity and imagination. Is it unlikely that under real-life situations Maple seeds don't fly as they do when a person throws them up under similar conditions of temperature, moisture, etcetera, etcetera? Would you -as a professional geneticist- really suggest Maples have not evolved flying seeds?

 

Rather than poo-pooing the general idea I have presented, wouldn't it be more fruitful if you addressed some of the specific mechanisms I have proposed? Yes; of course it would. If you find the experiments I have suggested as inadequate, then give your specific arguments to support your conclusion(s). Then too, you might propose experiments of your own.

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