Rhubarb, also known as rheum, turkish, and sometimes chinese himalayan, is an interesting plant. Its roots are medicinal, its stems, which must be cooked, are used to make delicious pies, and its leaves contain oxalic acid, making them poisonous. The plant is a perennial that reaches about ten feet. It has thick, brown roots and round hollow stems that end in multi-directional spikes of small flowers.Studies have shown that small amounts of rhubarb help relieve diarrhea and larger does help relieve constipation.