Rheum is a genus of perennial plants that grow from thick short rhizomes. The genus is in the family Polygonaceae, and includes the vegetable rhubarb (Rheum rhabarbarum or Rheum x hybridum.) The plants have large leaves that are somewhat triangular shaped with long fleshy petioles. The flowers are small, greenish-white to rose-red, and borne in large compound leafy inflorescences. Rhubarb is often consumed and a number of varieties are grown for their stems which are used in pies and other foods for their tart flavor.