Cattails

Get the roots of the cattails. Peel away tough leafy layers to the tender core, about 1/2 inch in diameter and maybe 12 inches long. This can be eaten raw, like celery, or sliced into a salad. Or, cover the cores with boiling water and simmer about 10 minutes. You may pick the green bloom spikes of the cattails, remove sheathes, and boil in water until tender, and eat like corn-on-the-cob.

From Edible Wild Plants: A North American Field Guide by Elias & Dykeman.