According to Wikipedia, “rhubarb is usually considered to be a vegetable; however, in the United States, a New York court decided in 1947 that since it was used in the United States as a fruit,it was to be counted as a fruit for the purposes of regulations and duties.”
So, it is a fruit.
Only stalks are edible. While you can eat them raw, most commonly 1-inch pieces of the stalks are stewed (boiled in very small amount of water) with sugar to combat their extreme tartness(1/2 to 3/4 cup of sugar is added for each pound of rhubarb) until soft. Use only a little water as rhubarb contains a lot of water itself and you risk to end up with rhubarb soup. In the US, rhubarb it is most often teamed up with strawberries / cinnamon/ nutmeg and baked into pies and tarts. A typical English preparation would use ginger; the French may puree it into a sauce and serve it with fish.
