Rhubarb

Rhubarb is a cultivated plant in the genus Rheum in the family Polygonaceae. It is a herbaceous perennial growing from short, thick rhizomes. Historically, different plants have been called "rhubarb" in English and used for two distinct purposes. The roots of some species were first used in medicine. Later, the fleshy, edible stalks (petioles) of other species and hybrids (culinary rhubarb) were cooked and used for food. The large, triangular leaves contain high levels of oxalic acid, making them inedible. The small flowers are grouped in large compound leafy greenish-white to rose-red inflorescences.

Rhubarb[en.wikipedia.org]
Rhubarb Festivals[www.pickyourown.org]