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Snow patch grass
Chionochloa oreophila

Diagnostic features for identification in the field

  • A short tawny green grass forming a turf of merging leaf tufts. Usually <20cm tall. Can form extensive grassy patches at high altitude.

  • Head of 4-8 spikelets borne on a slender stem above the turf.

  • Usually common in snowbanks, or less commonly on stable sites in fellfield.

References:
  • Mark, A.F. and Adams, N. 1996. New Zealand Alpine Plants, Reed Methuen.
  • Wilson, H.W. 1996. Wild plants of Mount Cook National Park, Manuka Press, Christchurch.

Description of community and habitat

 C. oreophila forms turf in late-snow banks, especially along and wet of the Main Divide.

East of the Main Divide, South Island
In Otago, C.oreophila occurs at high altitudes on the wetter ranges in West Otago e.g. Harris Mountains, Mt. Earnslaw, occupying hollows where snow lie is prolonged.

In the Waimakariri and Rakaia catchments in Canterbury, C.oreophila occurs in stable cirque basins.

West of the Main Divide, South Island
At Lewis Pass, C.oreophila occurs above 1700m, in areas of prolonged snow cover, resulting in only 4 months being snow-free.(Burrow, 1977). In Westland, Snow patch grass occurs with blue tussock (Poa colensoi) between 1300 to 1914m a.s.l., on gentle slopes (<15 degrees ), where it descends lowest on sahdy south facing slopes where snow lies late, and ascends highest on warmer north adn west facing slopes. This grassland occurs on deeper more weathered soils.

In Fjordland, snow patch grass is associated with mid-ribbed snow tussock (C.pallens), and occurs on recent soils on debris cones, fans and terraces.

This information was taken from: Wardle, P.; 1991. Vegetation of New Zealand, Cambridge Press, Cambridge.

Other species present

 East of the Main Divide, South Island
On cirque moraine and rock glacier material in the Rakaia catchment, snow patch grass occurs with Celmisia sessiliflora, blue tussock (Poa colensoi), Phyllachne colensoi and Raoulia grandiflora.

West of the Main Divide, South Island
In Westland, snow patch grass occurs with Carex pyrenaica and Poa colensoi in the deepest hollows, and with Marisippermum gracile on banks and risers of solifluction steps. Celmisia haastii, Anisotome flexuosa and Rytidosperma setifolium are also common.

In Fjordland, snow patch grass occurs in an association with mid-ribbed snow tussock C. pallens. Common species include Uncinia divaricata, Luzula rufa, Schizeilema haastii var. cyanopetalum, Oxalis magellanica, Geranium microphyllum, Viola cunninghamii, Oreomyrrhis colensoi and Leptinella squalida.

Information from: Wardle, P.; 1991. Vegetation of New Zealand, Cambridge Press, Cambridge.

Vegetation History

 These alpine grasslands are likely to have occupied similar habitats in the past as they do today. Because they occur in the higher rainfall areas, and at high altitudes, they have largely escaped the impacts of pastoral activities that have shaped the current distribution and condition of some other snow tussock grassland species. Feral animals may browse tussocks, however it is only moderately nutritious (Fenner et al., 1993), so that if other more palatable Chionochloa species are present, these are more likely to be favoured by ruminants in the field.

References:
Fenner, M.; Lee, W.G.; Duncan, S.J. 1993: Chemical features of Chionochloa species in relation to grazing by ruminants in South Island, New Zealand. NZ J Ecology 17(1): 35-40.

Burrows, C.J. 1977. 1977. Alpine grasslands and snow in the Arthur's Pass and Lewis Pass regions, South Island, New Zealand. New Zealand Journal of Botany 15: 665-86.





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