Often forming colonies stretching to 80-(160) m along sand dunes, with much-branched, knotted, rope-like, hard, creeping stems. Leaf-sheath leathery, strongly-nerved, silky-hairy. Hairs very dense to 6 mm. Leaf-blade c.300 mm, inrolled and c.1.5 mm diameter, leathery. The distinctive softly spiny female seed heads, which disarticulate and are usually seen rolling down the beach readily identify this species.

Strictly coastal where it is confined to sandy beaches. This is the main dune forming indigenous plant in New Zealand. It is usually found at the front of actively accumulating foredunes. Its does not tolerate stable dune systems and does not compete well with other introduced dune plants.

Uses sun's energy for photosythesis.

White flowers in September to December, fruits November to May. Indigenous. Common throughout New Zealand. Also present in Australia

http://www.nzpcn.org.nz/flora_details.aspx?ID=2266 accessed 13/02/14