Plant with tart red stalks used in pie filling

RHUBARB

This perennial vegetable is often mistaken for a fruit and pairs well with strawberries in desserts, though its leaves are toxic if eaten. Look for the name that starts with an "R" and sounds like a noisy argument.

This clue describes rhubarb, a vegetable often mistaken for a fruit because its tart, red stalks are commonly cooked with sugar and used in desserts like pies. The mention of "tart red stalks" points directly to rhubarb’s distinctive sour flavor and appearance, while "pie filling" hints at its popular culinary use. There’s no wordplay here—just a straightforward definition highlighting its key traits.