Across the UK
Carex Nigra. Also known as Black Sedge or Smooth Black Sedge likes sun or part shade, Drought Tolerant Zone AB
If ordered with other water/pond plants that are not ready but will be soon, your whole order may be kept back till all items can be sent together.
Common Sedge also know as Black sedge is a native, shallow water plant, that has blueish, vertical sword-like leaves. The flower-heads that are distinctively black when they emerge and the resulting seed heads are black too.