Rhubarb is a perennial vegetable that is a spring crop, and it is typically harvested from April to June. Although the plant thrives all through the summer. It is grown for its edible stalks. The stalks are typically red or pink, and they have a tart, sour flavor. They have big green leaves at the top, but those are toxic, so do not eat the leaves.  Rhubarb is a good source of dietary fiber and vitamin C. It is also a low-calorie food, making it a healthy choice for people who are watching their weight.