It’s been some time around that scientists, of the physiological kind, designed various way of measuring water flows in plants. Early measures mostly involved vascular plants (with an accent of sap), later analyses also involved those greenies that don’t produce vessels (e.g. Bryophytes), when the inner cellular nature of life was discovered and principles of osmosis were then more heavily investigated. All the stuff is usually packed up and taught within the classic water potential theory. I won’t dig deeper as an intro, because it’s been a long time that I went through all of this, and our teacher told us that we would only understand the stuff when we would dream about water potentials (at nights, he wasn’t really meaning we should sleep during the class). That dream never happened to me. But I suspect I hadn’t tried hard enough. There’s a reason why, and it is completely unrelated to the beauty of physiology and water fluxes in and out of a plant’s inner circuitry: I was rather highly sceptical of our teacher’s claims about dreams in general, or more specific clumsy claims (e.g., that we would understand chloroplastedness in front of Chartres’ Cathedral vitrals)*.
Now, plants happen to home many organisms that have the bad habit of feeding from them, or even more develop at their expense. Parasitism. Many fungi make a living on plants. Some divert a plant’s resource and drive it into producing galls (insects can do that too). And it’s not only a question of how much perverted growth and plant cell division results into a gall: as living structure that is now part of the host, a gall breathes and loses water as well! What amount of water is possibly lost ’cause of oblivious inhabitants that leave out such dripping spigots?
Turns out there’s a recent study measuring it**. (okay, it has specifics, it’s between Acacia implexa and its gall forming pathogen Uromycladium tepperianum if you want to know). The loss is of about 4.63%. It doesn’t look like big numbers, but that still about One twentieth of the water pumped out by the tree. I let you think about what happens during the dry season…
So when you’re accepting flatmates, don’t be cheap. Make sure they won’t be galling, or close the tap tight!
* Whereby you would understand that pseudoscientific inclination of a teacher won’t prevent you from succeeding in science, provided that it’s only sort of a “tragedy of the anticommons“. That is, as long as it is indeed a rare event. It probably won’t help you in mastering the specific field though.
** M. A. Forster (2012). Quantifying water use in a plant–fungal interaction. Fungal Ecology, 5 (6): 702-709.