Fluffy bulrushes

Bulrushes are scarce along this section of the canal. Most parts of the plant are apparently edible. The rhizome, can be eaten raw, cooked or dried for flour. Young shoots substitute for asparagus. Seeds are a food when roasted. Pollen from the flower has protein and can be added to flour. Plus the leaves can be woven. Why did I not know this before!
I need a good field guide to be sure before I eat a new foraged food. A well used quote is 'If in doubt leave it out'.