The stems of a rhubarb plant are treated as fruits in the kitchen – similar to celery stalks – even though they are simply herbaceous perennials.
However, rhubarb leaves are poisonous, and as they resemble spinach, they are always cut off the stem and sent straight to the trash. Humans have been poisoned after ingesting the leaves. This actually became a particular problem during the first World War when the leaves were mistakenly recommended as a food source in Britain.