Curly-leaved snow tussock (Chionochloa crassiuscula)

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Curly-leaved snow tussock
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Habitat

Other spp. present

Vegetation history

Background management information

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Curly-leaved snow tussock
Chionochloa crassiuscula

Diagnostic features for identification in the field

A small tawny green tussock (up to 45cm tall)
Leaves folds, with thick tips. Leaves characteristically curl spirally when dry or dead.
Head borne well above the leaves.

References:

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

Description of community and habitat

Curly-leaved snow tussocks occur in the higher rainfall mountains (between 1000 - 1800m a.s.l.) from Lewis Pass southwards. Whilst it is associated with ranges to the west of the Main Divide, it also extends eastwards in mid-Canterbury.

It is the most important plant near the upper limit of snow tussock-herbfield communities, but can extend down towards the treeline on cold southerly slopes or in seepage areas.

East of the Main Divide, South Island
Curly-leaved snow tussock grasslands occur infrequently East of the Main Divide. However, in the Waimakariri and Rakaia catchments, it occupies stable penalpine gullies of the eastern mountains.

West of the Main Divide, South Island
In Westland, curly-leaved snow tussock occupies mature, leached or boggy soils, where snow lies for up to 8 months of the year. Above 950m, it occupies deep wet hollows where water is forced to the surface, and at higher altitudes, on moderately gentle slopes with gley podzol soils.

In Fjordland, C.crassiuscula occupies similar sites i.e. leached soils which are shallow and wet, and on steep slopes.

Other species present

West of the Main Divide, South Island
In Westland, curly-leaved snow tussock occurs with shrubby plants e.g. Leucopogon pumila, Coprosma perpusilla, and herbs including Celmisia glandulosa, Gentiana bellidioides, Phylachne colensoi, Astelia lineata and Oreobolus impar. In Fjordland, Myrsine nummularifolia, Dracophyllum uniflorum, and Coprosma cheesemanii shrubs , Lycopodium fastigiatum clubmoss, and the herbs Aciphylla lyallii, Forstera sedifolia, Celmisia du-rietzii, Dolichoglottis scorzoneroides, Astelia lineata and Oreobolus impar.

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 not a Chionochloa species that is favoured by ruminants in the field. This is likely to be a reflection of it's poor content of protein, nutrient minerals and metabolisable energy (Fenner et al, 1993). It is likely that feral animals preferentially browse palatable intertussock herbs, thereby changing the species composition of curly-leaved snow tussocks.

Since curly-leaved snow tussocks occupy inaccessible high altitude gullies where it occurs in the eastern mountains, it is unlikely that sheep grazing would have had a significant impact on these grasslands.