Photographer's Note

Golden Sand Sedge or Pikao

These Pikao (or pingao) is also known as the Golden Sand Sedge and its botanical name is Desmoschoenus spiralis1. It is endemic to (found only in) New Zealand's coastal environment and is one of our major sand binders along with Spinifex sericeus (spinifex or kowhangatara) and Austrofestuca littoralis (Sand Tussock or hinarepe), trapping sand to create dune systems.

Pikao is a native perennial sedge. Sedges are similar to grasses but can be distinguished from grasses by examining the stem/blades in cross section. Sedge blades are triangular in shape whereas grasses form a straight line.

Pikao resembles tussock in appearance. The foliage is coloured a brilliant green which turn a golden yellow or fiery orange at the ends. The leaves are organised into tufts and are stiff and curled and rough to touch. These characteristics help to minimise moisture loss in the harsh coastal environment and probably afford some protection from salt spray. Pikao leaves turn a golden yellow when dried which is why Maori weavers prize them.

Pikao are limited by moisture, and a lack of sand movement. They are more tolerant to root salinity than marram grass and prefer exposed, unstable and bare sites. Pikao's morphology is dependent on location, as its habit varies from north to south
Pikao reproduce in two ways, vegetative (rhizomes) and sexually (seeds). Rhizomes are long woody rope-like vegetative structures resembling roots that are sent out from the parent plant. These contain nutrients, water stores and root initials that allow the rhizomes to establish into the sand and to send out leaves1. Rhizomes facilitate the dune building and stabiliation process by producing a large area of plant material and root systems to trap sand. The extensive root systems produced as a result of vegetative reproduction also allows greater extraction of water from larger masses of sand which is essential for pikaos' survival. Vegetative reproduction is the main means of reproduction in pikao, enabling plants to survive indefinately.
Seeds are produced sexually in the flowerheads. Pikao flowers are brown in colour and arranged in a spiral pattern (hence D. spiralis) on flowerheads that measure between 15-30cm in length. These are sent up from the plant on long sturdy stems. Seeds then develop on the flowerheads in spikelets6 and mature between December and February, depending on location (maturity is reached later in more southern, cooler locations).

Mature seeds are shiny, brown, egg-shaped and flat on one side however the exact shape depends on where the seed is located within the spikelet. Seeds also vary in size with the largest being about the size of a match head.

Wind dispersal is the primary mechanism for dispersal over short distance, whereas transportation via seawater allows dispersal over longer distances3. Pikao seeds appear to have a dormancy mechanism which ensures seed viability over the longer-term. Dormancy seems to set in shortly after seed maturity, after which germination may follow after the first year. The length of time seed may remain viable for is unknown. A natural seedbank of unknown age exist at Island Park, Dunedin. There had been no existing plants in the area, but plants appeared following sand disturbance at a DCC sand mining operation.

Thanks to Kara Scally on behalf of the Pikao Recovery Group.

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Photo Information
  • Copyright: Jim Stevens (Jimst) Silver Note Writer [C: 2 W: 0 N: 13] (205)
  • Genre: Places
  • Medium: Color
  • Date Taken: 2005-06-20
  • Categories: Nature
  • Camera: Olympus C-2020Z
  • Exposure: f/2.8, 1/125 seconds
  • More Photo Info: view
  • Photo Version: Original Version
  • Date Submitted: 2006-11-22 17:24
Viewed: 1631
Points: 6
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Additional Photos by Jim Stevens (Jimst) Silver Note Writer [C: 2 W: 0 N: 13] (205)
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