The sea rush, or Juncus krausii subsp australiensis is a plant I came across on my walk through Berowra Valley National Park (read here or here). It grows into tussocks that can reach at least one metre tall. Their habitat is in either saline or brackish water and does grow well in tidal marshland-it can occur in extensive stands of pure sea rush. While native to Australia along its coastline in all states except the Northern Territory, it is also native to New Zealand and South Africa. its binomial name Juncus krausii, has the following meanings:

• Juncus-comes from the Latin word jungere-to tie or bind. This is used as many rushes are used in weaving and basketry.
• Krausii-in honour of Christian Ferdinand Fredrich von Krauss (1812-1890). He was a German zoologist, naturalist, and museum keeper and collector in South Africa. He collected the type specimen for this species.

The leaves are up to 1.5 metres long, stiff and sharply pointed. They are only three millimetres in diameter.

The inflorescences appear in terminal spikes between December and March. The red to golden brown fruits follow the flowers in clusters.

Indigenous Australians use the stems for fibre, including for things like fishing lines, woven rugs and baskets. Today, the sea rush is also used as a way to help stabilise estuary banks and river banks and around salt marshes, especially around areas of urban development. It also gets used in bioinfiltration systems and rain gardens.

https://syzigium.xyz/saplants/juncaceae/juncus/juncus_krausii.html

Robinson, L., Third Edition, 2003, Field Gude to the Native Plants of Sydney, Simon & Schuster, Sydney

Fairley, A., & Moore, P., Third Edition, Native Plants of the Sydney Region, Allan & Unwin