Rhubarb is the common English name for a number of plants of the genus Rheum, grown for food, as an ornamental, and in herbal medicine. Even with the popular culinary type, a favored ingredient in rhubarb pie, the preparation and handling must be well understood because the leaves contain toxic quantities of oxalic acid. The stalks are the edible part, although the rhizome is used medicinally.
In warm climates, rhubarb may grow year-round, but it is most successful in cold climates, where it dies back completely in winter and regrows in Spring. In North America, it is a cool-weather plant that appears early and is harvested early. Texas A&M University observes it grows poorly in the South. 
'Rhubarb can not be very successfully grown in the southern regions of the United States, although there are exceptions.... If it survives the heat it will not grow well will produce only thin leaf stalks which are spindly and lack color.'
Rhubarb is rather sour if tasty, and is often sweetened in jams or pies. It blends well with strawberries.
The species Rheum palmatum contains a large number of biologically active substances.
"Rhubarb" is British slang for a disagreement. During the Second World War, it was a code name for "low-level strike operation mounted in cloudy condition against enemy targets in Occupied Countries". The operation was usually intended as offensive counter-air against Luftwaffe facilities.