Owing to the wet climate of most parts of New Zealand, forest, scrub, and fern were the major plant coverings when European settlement began. Except in tussock grasslands, native grasses formed only a minor part of original vegetation. The number of genera of native grasses is given as 33 in Cheeseman'sManual of the New Zealand Flora. Only one genus, the rare Simplicia, is confined to New Zealand. Cheeseman described 123 indigenous species and remarked “in addition …, a large number of grasses have become naturalised, and that every year adds to the list. Most of these are natives of the Northern Hemisphere, and many have been purposely introduced and widely spread through the country on account of their value for pasturage or fodder. The remainder are either weeds of cultivation or inhabitants of waste-places or roadsides, a large proportion having followed the footsteps of civilised man all round the world. A few Australian and subtropical species have also established themselves, but the number of these is not nearly as large as might have been anticipated. Many of the naturalised species have so completely amalgamated with the indigenous flora as to present the appearance of true ‘natives’….” In 1940 H. H. Allan described 92 naturalised grasses and noted that many species are common throughout New Zealand. (Pending the issue of Parts 2 and 3 of the Flora of New Zealand, by H. H. Allan, which will contain a revision of the grasses, the names used are those given in Cheeseman's Manual of the New Zealand Flora, 1925.)
Before the arrival of the first European settlers in New Zealand, tussock grassland covered most of the land east of the main divide in the South Island. In the North Island small areas on the Volcanic Plateau and in Hawke's Bay were similarly covered. These were not natural pastures as apart from birds, there were no grazing animals and most of the grasses were tuft-like and grew in clumps. Known as “tussock grasslands”, these areas provided a certain amount of food for introduced stock — the small plants growing in the shelter between the tussocks often being more palatable than the tussocks. It was also found that the new growth, which came away from the crown of the tussock after burning, was acceptable to stock. There followed the practice of periodic burning which, together with the grazing of sheep and invasion of rabbits, resulted in the destruction of much low-tussock country. Lowland tussock was easily ploughed and sown with introduced grasses, and as a result the plains of the South Island were developed for farming more rapidly than the forest-clad North Island.
Hard tussock (Festuca novae-zelandiae) and silver tussock (Poa caespitosa) are dominant grasses of low-tussock grassland. Blue Poa (Poa colensoi) and Agro-pyrum scabrum become prominent in Otago. Other grasses associated with low tussock are Danthonia pilosa, Danthonia semiannularis, Deyeuxia avenoides, Triodia thomsoni, Poa colensoi.
In the tall-tussock grasslands where red tussock (Danthonia rubra) is dominant, other grasses found are Hierochloe redolens, Danthonia setifolia, and Poa caespitosa. Where snow grass (Danthonia flavescens) predominates in the high altitudes, other grasses are Agrostis dyeri, Deyeuxia avenoides, and species of Trisetum. Although snow grass and red tussock are of little use as food for stock, they are valued for shelter and for protection given to the soil. By means of their roots all grasses help to fix the soil and prevent erosion, and tall tussock can play an important part in this way in mountain areas.
In 1935 Allan reported that a South American grass, Nasella tussock, was established at Waipara River, Omihi Valley, and Amberley. The grass is a pest in sheep country and strenuous action has been taken to destroy or contain it.
On the coasts of the North Island and the northern part of the South Island, the silvery sand grass (Spinifex hirsutus), whose large seed heads bowl along the beaches in the wind, grows on the moving sand of the foredunes, and is a useful sand binder. Haretail grass, Lagurus ovatus, introduced from Europe about 1873, now covers the dunes in many places and also occurs in Central Otago. Throughout New Zealand the feathery panicles of Deyeuxia billardieri are a feature on fixed dunes. A native fescue, Festuca littoralis, occurs on sandy or rocky places near the shore. The small mat-forming Zoysia pungens is common as far south as Banks Peninsula. It is a hardy native, suitable for lawns in arid conditions.
The salt grass, Atropis stricta, grows on the wet mud of salt marshes with a native paspalum, P. distichum. At a slightly higher level in the marshes, tussocks of Stipa form a conspicuous belt.
Coastal cliffs are the habitat of the straggling New Zealand Bamboo, Microlaena polynoda, the nodding Poa, P. anceps, and blue grass, Agropyrum multiflorum.
On sandhills, river banks, flax swamps, and hillsides throughout New Zealand the tall graceful toetoe, Arundo conspicua, is one of the best-known native grasses. It has been replaced in many localities in the Auckland Province by pampas grass, Cortaderia dioica. This was planted for cattle food, but has escaped.
In dry, open, lowland situations, the hairy and ringed Danthonias, D. pilosa and D. semiannularis, are common. In the north they have been supplemented by the introduced paspalum to form summer pastures. As well as the Danthonias, a number of native grasses are palatable to stock, for example the blue wheat grass, Agropyrum scabrum, Deyeuxia quadriseta, Echinopogon ovatus, Dichelachne crinata, Hierochloe redolens. They do not form an important part of the pastures of New Zealand, however, where introduced grasses are more common.
In second-growth forest in the North Island, creeping mats of Oplismensus undulatifolius suggest that this native might be a useful lawn and cover grass in shaded positions.
The slender Poa, P. imbecilla, and bush rice grass, Microlaena avenacea, occur in forest clearings throughout New Zealand, but their recognition is difficult among the wealth of vigorous foreign grasses that follow man everywhere.
by Jeanne Hannington Goulding, Botanist's Assistant, Auckland Museum.
- The Indigenous Grasses of New Zealand, Buchanan, J. (1880)
- Manual of the New Zealand Flora, Cheeseman, T. F. (1925)
- D.S.I.R. Bulletin No. 49 (1936), “An Introduction to the Grasses of New Zealand”, Allan, H. H.