The New Zealand Plant Conservation Network

This plant is growing in the northern Wairoa River at Dargaville

Added a second photo that might help ID

Schoenoplectus californicus. I will write more about it later

Hi Phil - Schoenoplectus californicus is easily recognised by its robust growth habit, culms with are terete (circular) in the lower third to half and trigonous in the upper 2/3 to half and pendant inflorescences. It is well naturalised in the lower Wairoa River and around Port Waikato, and has been widely planted (usually in error as people thought it was the indigenous S. tabernaemontani) for use in wetlands treating effluent. It is a very aggressive species. For more information see: de Lange, P.J.; Gardner, R.O.; Champion, P.D.; Tanner, C.C. 1998: Schoenoplectus californicus (Cyperaceae) in New Zealand. New Zealand Journal of Botany 36: 319-327. Download it free at: http://www.tandfonline.com/toc/tnzb20/36/3#.U-a6sqOc4ig

Peter I thankyou for the time you put into your reply.
I appreciate it.

Cheers Phil

No worries. All part of "the service!". :-)

Great work Peter, thanks!