Cow parsnip is a large wild perennial herb in the carrot family (Apiaceae), native to North America, with big flat-topped clusters of white flowers and hollow, ridged stems that can grow over 6 feet tall. It's often confused with giant hogweed (Heracleum mantegazzianum), a related but distinct and more dangerous species introduced to North America from Asia; cow parsnip's sap is phototoxic but generally causes milder burns than giant hogweed's.
Indigenous peoples across North America have long eaten the young stems, leaves, and flower buds of cow parsnip raw or cooked, along with the roots, which are woodier and more fibrous. The flavor resembles celery or parsley, with a mild bitterness. In the kitchen, stems and leaves can be boiled, sautéed, or added to soups and stews; flower buds are pickled or used as a garnish; roots are roasted or mashed.
Because the sap can cause severe skin blistering when exposed to sunlight, anyone harvesting or handling cow parsnip should wear gloves and long sleeves, and should be confident in the identification before eating any wild Apiaceae plant - several of which, including giant hogweed and poison hemlock, are toxic look-alikes.