Rhubarb is recognized as Rheum rhabarbarum and is a member of the Polygonaceae family. Rhubarb leaves are toxic, but they are also bitter. Needless to say, rhubarb leaves are not edible.
The stalks of rhubarb are edible part of the plant. It grows as a silverbeet with dark red stems eaten as a sweet and savory products. It is often assumed that rhubarb is a fruit, because it is most often used in sweet dishes such as pies, jams and cakes, but is actually a vegetable used in sweet dishes. The fruit of the plant that contains the seeds, stalks of rhubarb as we eat, is wrong to call it fruit. While developments in America at the end of 1940, stated that since it was used as a sweet foods it must be declared fruit.
Rhubarb grows throughout the summer in cooler regions, but can be grown throughout the year, if grown in a greenhouse, protected from the cold and frost. Historically, first mention of rhubarb seems to be in China, where it says date back beyond 2500BC. Rhubarb made its first appearance in America in the early 1800s.