Description - from Wikipedia

Isolepis cernua (basionym Scirpus cernuus) is a species of flowering plant in the sedge family known by the common names low bulrush, slender club-rush, tufted clubrush, and fiberoptic grass. It is widespread, being native to many regions of the world, including parts of Australasia, Eurasia, Africa, and North and South America.
I. cernua is a small sedge that can be common in boggy ground and around ponds in both freshwater wetlands and salt marshes, as well as among dune slacks and other brackish environments.

References
External links

Online Field guide to Common Saltmarsh Plants of Queensland
Jepson Manual Treatment
Washington Burke Museum
Flora of North America
Photo gallery
Gardeners World
New Zealand Plant Conservation Network