Rhubarb (Rheum rhabarbarum) is a species of plant in the family Polygonaceae. It is a herbaceous perennial growing from short, thick rhizomes. It produces large leaves that are somewhat triangular, with long fleshy stalks and small flowers grouped in large compound leafy greenish-white to rose-red inflorescences.
In culinary use, fresh raw leaf stalks (petioles) are crisp (similar to celery) with a strong, tart taste. Most commonly, the stalks are cooked with sugar and used in pies and other desserts. A number of varieties have been domesticated for human consumption, most of which are recognised as Rheum x hybridum by the Royal Horticultural Society.