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Nothing serious or that I'm worried about, just something I was musing on out of curiosity.

Plants pearl when they're photosynthesizing rapidly, and they're producing oxygen fast enough that it can't dissolve as usual into the already saturated water in contact with their surface; so instead they release gaseous oxygen through their pores. So I've been told.

The thing is... I'd imagine a plant is covered with lots of pores, but when my plants pearl I see a lot of bubbles coming from a surprisingly small number of spots on the plant, often several inches distant from parts that should be producing the most oxygen.

I try to imagine why this is in my mind's eye, and this is what I see happening inside the plant:

Oxygen forms microbubbles inside the plant's tissues. These bubbles grow, increasing in pressure until they push their way into the plant's circulatory system, possibly ripping small tears in the plant's inner tissues in the process. Bubbles continue to accumulate and combine there until the increasing pressure finally opens an outlet to the outside, either by forcing open an existing pore or by creating a rupture. As the bubbles stream out the small hole from several inches of plant, it pushes out the plant's nutrient-rich sap from that area along with it.

Any thoughts on this? Scientific references? Do I have an overactive imagination? :)
 

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I see a lot of bubbles coming from a surprisingly small number of spots on the plant
You mean those bubble streams that usually come out of cut ends or damaged spots?

I came by this article and thought this excerpt might interest you:
An important adaptation for many freshwater aquatic plants is the formation of aerenchyma, which is parenchyma tissue having large intercellular air spaces. Aerenchyma functions both to store oxygen and to transport that gas to living tissues. This gas collection is important in leaves for buoyancy. In addition, the system of lacunae is a diffusion pathway for oxygen; the oxygen is, of course, made in the chloroplasts during the light reaction of photosynthesis. Oxygen, when released via photosynthesis, diffuses preferentially into the lacunae, because it cannot diffuse as rapidly into water and comes out of solution in the intercellular air spaces, where oxygen concentration of trapped air there may be one-third or greater. Here it can be used in constructive ways by aquatic plants. A leaf midvein, petiole, or stem develops an internal pressure, which enables oxygen to be transported via bulk flow in a lacunar network to rhizomes and roots located in the anaerobic mud and muck, permitting these organs to grow more rapidly. Gases can also move in bulk to young tissues, where the pressurized air helps expansion of developing lacunae near the growing tip. The cut end of an aquatic plant will give out bubbles (underwater, of course) from lacunar gas under pressure.
 

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The vascular tissue in plants is fairly difficult to break into from a bubble's point of view.

Although the aerenchyma is interesting, what's the advantage of oxygenating its tissues, unless anaerobic conditions are not conducive to root/rhizome growth.
 
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