Raw rhubarb is edible. The leaves of the plant are poisonous according to the National Institutes of Health, and should be removed and discarded before the raw rhubarb stalks are consumed.
Rhubarb stalks, also known as petioles, have a crunchy, ribbed texture similar to that of celery. They possess a fruitier, tarter taste than celery, which is why they are typically sweetened in most recipes. When eaten raw, rhubarb stalks are most palatable when dipped in sugar or honey. Rhubarb leaves, however, contain oxalic acid, a toxin that can cause kidney failure, difficulty breathing and nausea, according to the National Institutes of Health. It is important, before consuming raw rhubarb, to cut off and throw away the rhubarb leaves and wash all surfaces, including the petioles, that have come into contact with the leaves.