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Bristle tussock
Rytidosperma setifolium

Diagnostic features for identification in the field

  • This small tussock is similar to Poa colensoi. Check that it as a hairy ligule, and that awns are present.

  • A small tussock ~ 25 - 35 cm tall. Leaves yellow to bright green, rolled, smooth with sharp point.

  • Sheaths persistent; pale and not hairy. Ligule at base of leaf is hairy i.e. a rime of hairs with axillary tufts present.

  • Flower stalk is borne above the leaves (~50cm tall). Not hairy.

  • Flower head is erect and open. Distinctive orange anthers and bent long awns.

    Habitat summary:
    • Mountain environments from lowland to high alpine (1800m), throughout South Island, but common in North Canterbury and Marlborough.
    • Common in dry, rocky environments and degraded tussock grasslands

References:
  • Mark A.F. and Adams, N. 1996. New Zealand Alpine Plants. Reed Methuen.
  • Jane, G. 1995. 1995, Field guide to grasses. 1. Alpine grasses.



Description of community and habitat

 Bristle tussock is common in dry areas of mountain regions (lowland to 1800m) throughout the South Island, especially on rocky outcrops, or in open depleted snow tussock grassland in Marlborough and North Canterbury.

East of the Main Divide, South Island
Bristle tussock is most common in Marlborough and north Canterbury, where the rainfall is relatively low, and the greywacke bedrock is eroding. A history of burning and grazing has resulted in the replacement of snow, fescue tussock grasslands or even beech forest by a non-continuous grass cover, especially on warm faces. Such areas can have the appearance of a fellfield, rather than a grassland.

In wetter areas closer to the Main Divide, bristle tussock is found in avalanche chutes, where frequent disturbance prevents the establishment of more stable vegetation communities.

West of the Main Divide, South Island
Bristle tussock can be found on alluvium and fine moraine above 950m. Slips and fractured rock are pioneered by bristle tussock to 1550m.



Other species present

 East of the Main Divide, South Island
In depleted grasslands in Marlborough, bristle tussock is commonly found with blue tussock (Poa colensoi). It is also associated with blue wheat grass (Elymus solandri), Celmisia monroi, Celmisia spectabilis, alpine fescue tussock (Festuca matthewsii), and mid-ribbed snow tussock (Chionochloa pallens).

At Mount Cook National Park, bristle tussock is associated with blue tussock (Poa colensoi), native willowherbs (Epilobium pycnostachyum, E. glabellum), native hairbell (Wahlenbergia albomarginata), everlasting daisies (Helichrysum bellidioides), Blechnum penna-marina, and at higher altitudes, Agrostis subulata, Poa novae-zealandiae, Epilobium porphyrium and the occasional Olearia mochata shrub.

West of the Main Divide, South Island
In Westland, bristle tussock is associated with blue tussock, Microlaena colensoi and everlasting daisies (Helichrysum bellidioides) in rocky sites.

Reference:
  • Wardle, P.; 1991. Vegetation of New Zealand, Cambridge Press, Cambridge.



    Vegetation History

    Much of the high country was covered in beech forest until about 700 to 900 years ago, whilst the moister parts of inland basins lost it's podocarp and beech forest cover around 1000 years and 2000 ago respectively. Short tussock species naturally occurring in areas too dry for forest, or in open enclaves within the forest, migrated from these sites, upslope. At the same time, tall tussock species were migrating downslope from their alpine environments, and gradually replaced the short tussock grasslands, over a period of 200 years.

    Since European settlement, these tall tussock grasslands have been repeatedly burnt and grazed, often with the aim to reduce the cover of the tall tussocks in favour of the more palatable short tussock species. More recently, many of these short tussock grasslands have been the focus of pastoral development programmes, which has increased the soil fertility and introduced exotic pastoral species. In Marlborough and North Canterbury, severe depletion of snow tussock, fescue tussock or even beech forest, through excessive burning and grazing, has resulted in the open bristle tussock grassland present today.

    References:
    • Wardle, P. 1991. Vegetation of New Zealand, Cambridge Press, Cambridge.
    • Connor, H.E. and Macrae, A.H. 1969. Montane and sublapine tussock grassland in Canterbury. Chapter 9 in: Knox, G.A. (Ed.). The natural history of Canterbury, pp 167-204. Reed, Wellington.