scale bar = 1cm.
  Streaked Arrow-grass - native (Triglochin striata)
 
 
Family: Juncaginaceae.
Cosmopolitan.
Occurrence: Uncommon.  Grows in open water.
Identification:
- the leaves are long and narrow
- the flowers are along an erect slender stalk
- the fruit are shortly stalked.
Image: Streaked Arrow-grass. Tullaroop Reservoir.