Answer: There's a plant called butter-bur (also known as Japanese coltsfoot) that fits the description you give. The botanical name is Petasites japonicus. This giant perennial prefers to live in moist places - especially near ponds. The leaves are 2 1/2 feet wide on 3 foot long stalks. The stalks are harvested by the Japanese and used as a vegetable called fuki. Beware! This plant spreads by rhizomes and is invasive. It's very difficult to eradicate once it gets a foothold in a garden!
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