Here are two things about rhubarb that you might not know, that you might find interesting, but that might put you off of using that red, tart, delicious celery lookalike:

Thing one is that the use of rhubarb as food is a relatively recent innovation, dating back in Europe only to the seventeenth century, according to the Wikipedia. Until then, rhubarb was used medicinally — as a laxative. Apparently, in Europe, in China, in the Middle East, and elsewhere, if you went to the doctor complaining of being stopped up, a strong dose of rhubarb was the cure.