This picture shows where the specific name 'nigra' comes from - the dark brown to black flowers and seed heads.

Once harvested in vast quantities from the Fens for roofing: either complete roofs were made from it, or it was used to finish the longer-lasting reed thatch. Sedge, unlike reed, is quite pliable and can be bent to form a ridge and around the gables. It does not, however, last as long - only about twenty years compared with sixty or more for best Norfolk reed.