Bake at 350 oven for one hour or until veggies are done. This will not damage the roots, so next years cattails are safe. Remove the leaves and outer portion of fronds. Cattail stalks can be eaten raw and used like an onion. The clear syrupy juice of cattail is a good thickening agent for soups.
Cattail roots are edible too and are a good source of carbohydrates and starch.
Steamed Cattails Cover the stalks with boiling water and simmer for 10 minutes or until tender. Add 5-10 small tender garlic mustard leaves or top with nut butter.