I was absolutely thinking of Iroh considering a plant for tea when writing this one. “Delectable tea? Or deadly poison?” – The last airbender is the best show in the world. And that is a fact, but not the fact I’m focusing on today.
I love rhubarb, and I have fond memories of sitting in the garden and dipping the stems in sugar as a kid. I was relieved to not have eaten any of the leaves when I learned they were poisonous, but after looking in to it, I never really had anything to worry about. As compungchem said it: “The suggested lethal dose of oxalic acid is in the region of 15-30 grams, meaning you’d have to eat a fair few kilograms of the leaves to reach this dose, but lower doses can still cause nausea and vomiting.” ( http://www.compoundchem.com/2015/04/16/rhubarb/ last accessed 13.04.2021). So it is definitely poisonous, but the risk of getting severely poisoned from this plant is severely low.
However, I was curious to find out how a serious oxalic acid poisoning would present, so I found this article:
Dassanayake U, Gnanathasan CA. “Acute renal failure following oxalic acid poisoning: a case report”. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3527234/ last accessed 13.04.2021), this was not from eating rhubarb, because, hello.. who eats several kilos of leaves in one sitting, but you can give it a read if you want.