Nelson Area

Although the flora of the Southern Alps is much better known than that of any other parts of the South Island some differences are seen in northern areas on the Dun Mountain in Nelson and the Kaikoura Ranges.

The Dun Mountain is part of the “Mineral Belt”, the rocks of which are peridotite and serpentine. A luxuriant forest of southern beech suddenly ceases on the serpentine and is replaced by tall tussock grassland and short, stunted trees. That there are differences in the soil is shown by the growth of trees such as the broadleaf (Griselinia littoralis) and southern beech (Nothofagus fusca). The ground is stony and vegetation is sparse. Cassinia vauvilliersii (mountain cottonwood); the tangled woody branches of Hymenanthera dentata; a grass tree, Dracophyllum rosmarinifolium; all appear to be able to live in these dry conditions. Of smaller plants are the prostrate shrubby Pimelia suteri, the yellow forget-me-not Myosotis monroi, and a rosette plant Nototholapsi australe, similar to the “penwiper” plant of the shingle slips.

In the Kaikoura Mountains three species of Heli-chrysum are common: H. microphyllum, H. selago, and H. coralloides. Geum uniflorum and G. avens are found in pockets of peaty soil among rocks. The yellow-flowered Ranunculus lobulatus is known as the “Kaikoura buttercup”. There are many parts of these mountains which have not been explored from a botanical point of view. On screes in these northern parts of the South Island is the dwarf succulent, with its dark leaves, Wahlenbergia cartilaginea, seldom found elsewhere; also Hebe epacridea, H. pinguifolia, and H. decumbens.

The Southern Alps

In the South Island ecological factors are much more apparent than in the north, and there is a marked difference between the vegetation growing on the eastern and western sides of the Southern Alps. On the former, the rocks in the main break easily, hence the many barren screes. It is probable that the eastern slopes may have been covered by forest, later destroyed by fires both by Maoris and early Europeans. Sheep and cattle have no doubt destroyed other vegetation. The alpine vegetation on the western side has changed but little. There is still the luxuriant rain forest, with the beech forest further south. The tree limit varies but in the Southern Alps the forest reaches to over 4,000 ft; above this are the snow tussocks and the herbfields. Flowering plants have been recorded at 9,000 ft, and in sheltered crevices have been found Hebe haastii, Celmisia discolor, and Ranunculus sericophyllus and, above Lake Hawea, Raoulia youngii. It is difficult to find these plants among the shifting stones at these great heights as the general colouring blends with that of their surroundings. Two plants of matted growth-form and tiny leaves are Donatia novae zealandiae, found where there is trickling water, and Phyllachne clavigera both growing in places where it would seem plants could not live. At lower levels are other species of Phyllachne, often covered with masses of snow-white flowers. Hectorella caespitosa is a perennial dwarf shrub of cushion habit found in high altitudes from Arthur's Pass southward, and of similar distribution is Parehebe birleyi, which grows on exposed crags at very great heights. Closely related to the Hebes is Pygmea, two species of which are found in high altitudes. P. pulvinaris forms very small, grey-green rounded cushions in the northern parts of the Southern Alps. It flowers as the snow retreats, at 4,500 ft in November, but later in the season at a much higher altitude. P. tetragona has a more open habit of matted woody branches and large flowers and is found on barren stony summits towards the south.

Mountain Screes

Among the shifting mass of stones on steep slopes it is amazing that plants manage to survive; these have long rhizomes penetrating to damp spots, and succulent leaves covered by hairs. The individual plants are widely scattered but it is interesting to note that of nine species recorded, each belongs not only to a separate genus but also to a distinct family, quite unrelated to the others, though most of the genera are represented by other species in the surrounding country. These species are: Stellaria roughii (Cary-ophyllaceae), Ranunculus haastii (Ranunculaceae), Anistome carnosula (Umbelliferae), Acaena glabra (Rosaceae), Notothalpsi rosulatum (Cruciferae), Cotula atrata (Compositae), Epilobium pycnostachyum (Ona-graceae), Lobelia roughii (Lobeliaceae), and Poa sclerophylla (Gramineae). There are other plants which grow on screes but are not confined to them, being found also between and on rocky crags. Among such plants are Craspedia incana, which appears as a white mass with yellow flowers, Myosotis traversii, Hebe epacridea, and Senecio glaucophyllus; species of Haastia grow at the edges of screes but their roots penetrate firmer substratum. Shingle gives place to more stable substratum, sometimes called a fell-field, where growth-forms are prostrate shrubs, cushion and rosette plants, semi-woody thick stemmed shrubs, and tussock grasses. Among such plants are several species of Celmisia – C. laricifolia, C. discolor, C. viscosa, C. sinclarii, C. haastii; some species of Dracophyllum, Hebe pinguifolia, and similar species of this large genus; broad green mats of Ourisia caespitosa; the creeping mountain foxglove; large cushions of Raoulia grandiflora; and the mountain totara, Podocarpus nivalis. On the western side of the Southern Alps and on mountains of the North Island a similar area with much more dense vegetation is known as a herbfield. There the conditions are better and there is a more plentiful supply of water; the plant covering is thicker and the growth more luxuriant. In addition to the foxglove, buttercup, and bog celmisia of the Egmont herbfields, and the alpine astelia and edelweiss of the Tararua-Ruahine mountains, the South Island herbfields have the beautiful Ranunculus lyallii, often acres of it which when in full bloom is a glorious sight. There are more species of Celmisia and Ourisia with showy flowers. Further to the south the species are slightly different but the main types still flourish.

Sub-alpine Scrub and Bog Species

Between the herb fields and the forest are belts of sub-alpine scrub which often becomes impenetrable owing to the interlacing branches of shrubs and stunted trees. There are great numbers of species found in various plant associations and these belong mainly to the genera: Hebe, Olearia, Senecio, Nothopanax, Dracophyllum, and Aciphylla, along with manuka, tussock grasses, bracken fern, and stunted beech trees. Cushion and matted forms of growth of Raoulia and Haastia, as well as of other plants, are common on slopes exposed to the wind.

On some mountain slopes are areas of bog. In these and in areas of peat, at edges of streams and similar places, are Donatia novae-zelandiae, Senecio lyallii, species of Ranunculus, Carex and Drosera, and cushions of Celmisia argentea. A very common plant in damp peaty soils, at moderate altitudes, is the Maori onion, Chrysobactron hookeri, which produces masses of yellow flowers. This, like the two Cassinias sometimes found in sub-alpine regions, C. leptophylla and C. vauvilliersii (cottonwoods or tauhinu), is not attractive to sheep which avoid also the wiry stems of Cyathodes spp., common among the tussock and providing a patch of colour when covered by white and red berries unusually large for the size of the flowers. In similar places are some of the smallest Coprosmas, C. petriei and C. pumila, forming mats which bear tiny, almost colourless, unisexual flowers but bright orange-red berries. On the edges of moraines and in river beds the willow-herb, Epilobium, is represented by E. microphyllum, E. tenuipes, E. erubescens, and E. melanocaulon. Here also are Muehlenbeckia axillaris, Discaria toumatou, Helichrysum microphyllum, H. selago, H. coralloides, Craspedia minor, and a few species of yellow-flowered forget-me-not (Myosotis). Cyathodes fasciculata mingimingi), C. fraseri, and C. empetrifolia are found in rocky places, together with Euphrasia monroi, E. revoluta, E. petrei, the profuse-flowering tiny Pimelia prostrata (New Zealand daphne), the large, very hardy, and more erect species, P. traversii, and P. aridula, particularly common in Marlborough and Otago.

Southernmost Regions

Lacking the long backbone of the Southern Alps, the ecological factors in areas of Otago, Southland, Fiordland, and Stewart Island are somewhat different, resulting in different plant associations and in each of these areas are a few species confined to a particular locality. The genera with which we are familiar are represented in these southern parts by different species. For example, here are Ourisia macrocarpa, O. caespitosa, and O. gracilis (var.), and in Fiordland and Stewart Island is found O. sessilifolia.

In the dry alpine areas of North Otago are certain species seldom found elsewhere: Acaena buchananii, Hebe buchananii (with thick bluish-green leaves), Carmichaelia petriei, and two other unusual species of Carmichaelia. This is a barren-looking area as there is no forest, only a few trees in sheltered gullies, and large areas are covered by snow grass. Much damage has been done in these parts by rabbits. This area merges into Southland where localities with a southerly aspect receive some heavy rains. Most of this area was covered by forest, mainly of rimu, kamahi, and some southern rata (Metrosideros lucida), with tall tussock and some hebes. There are also extensive sphagnum bogs.

Cushions of Pygmea myosotoides, P. thomsonii, and P. tetragona are common. Celmisias in these southern areas are Celmisia hookerii, C. thomsonii, C. coriacea, and C. verbascifolia; while of Hebes those of southern distribution are H. laingii, H. haastii, and Parahebe canescens. These extend to Stewart Island. Species found only in South Otago are H. poppewellii, H. annulata, and Celmisia poppewellii. The South Otago area has many species in common with Fiordland such as Ranunculus buchananii, Aciphylla pinnatifida, Dracophyllum menziesii. In Fiordland there are extensive beech forests of Nothofagus fusca and N. menziesii, and two buttercups not found elsewhere, Ranunculus matthewsii and R. baughanii, also an abundance of R. buchananii. The genera Ourisia, Olearia, Celmisia, and Senecio are each represented by local species. Putaputaweta (Carpodetus serratus), and Olearia oporima, O. angustifolia, and O. avicenniaefolia are common about Bluff and Stewart Island. Though there is little ground rising above 3,000 ft in altitude, much of the vegetation of Stewart Island is of the high-mountain type, such as Celmisia argentea, Donatia novae zelandiae, and Senecio lyallii.

In the southern alpine areas snow lies long. Cold rain and gales and cloudy days are frequent and these conditions are reflected in the vegetation; plants which are high-mountain plants further north are here found at much lower levels. Many species are seen growing under a great variety of conditions, and so many variations of growth form are found that the classification and identification of species and varieties are difficult. But from the viewpoint of the New Zealand botanist, the flowers of the mountains are both a delight and a rewarding study.

by Olive Rita Croker, M.A., Botanist, Wellington.

• Rock Garden Plants of the Southern Alps, Phillipson, W. R. and Hearn, D. (1962)
• The Flora of Mount Cook, Arnold Wall (1925)
• New Zealand Plants and their Story, Cockayne, L. (1927)
• Plants of New Zealand, Laing, R. M. and Blackwell, E. W., 3rd ed. (1927)
• Manual of New Zealand Flora, Cheeseman, T. F. (1906)
• New Zealand Flora, Allan, H. H. (1961).