Rhubarb (Rheum Rhaponticum, Polygonaceae) is a perennial plant that grows from thick, short rhizomes. The large, somewhat triangular leaf blades are elevated on long, fleshy petioles. The flowers are small, greenish-white, and borne in large compound leafy inflorescences.
The plant is indigenous to Asia, but is now grown in many areas, primarily for its fleshy petioles, commonly known as rhubarb sticks. These can be cooked in a variety of ways. Stewed, they yield a tart sauce that can be eaten with sugar or used as filling for pies, tarts, and crumbles.
During the winter it disappears completely and begins to grow in early spring. It can be forced, that is, encouraged to grow early, by raising the local temperature. This is commonly done by placing an upturned bucket over the shoots as they come up.
The drug rheum is prepared from the rhizomes and roots of another species, Rheum officinale or Medicinal Rhubarb. This species is also native to Asia. Rheum is used as a strong cathartic and for its tonic effect on the mucous membranes of the nasal cavity.