Forest Vines to Snow Tussocks: The Story of New Zealand Plants
The Commoner Species of the Forest Strata
The Commoner Species of the Forest Strata
Conifers are prominent in this usually discontinuous stratum, with rimu (Dacrydium cupressinum) the most common in a range of reasonably moist sites on flats, slopes and ridges. The light-demanding and droughttolerant totara (Podocarpus totara) favours stony river terraces and similar level areas, while kahikatea (Dacrjcarpus dacrydioides) prefers moister places often near streams. Miro (Prumnopitys ferruginea), the most shade tolerant of the conifers, and matai (Prumnopitys taxifolia) are not quite so tall as the three preceding species and are not always emergent. Miro occupies a similar range of sites to rimu, and matai is most abundant on fertile alluvial or volcanic ash soils. As totara, kahikatea and matai thrive on younger fertile soils they are most prominent during the first centuries of forest development.
Although not tall trees, at higher altitudes Hall's totara (Podocarpus hallii) and the attractive conical mountain cedar or kaikawaka (Libocedrus bidwillii) may be emergent above a low forest canopy.
Some flowering trees also contribute to this stratum: northern rata (Metrosideros robusta) because it commences its life on a rimu or other tall tree; pukatea (Laurelia novae-zelandiae) in association with kahikatea in moist places; and rewa rewa (Knightia excelsa). The last with its distinctive 'lombardy poplar' form is sometimes abundant on hill slopes, but usually in relatively young forests.
The emergent conifers range throughout the country. Of the three flowering trees rewa rewa and northern rata reach their southern limits in the northern South Island, while pukatea extends to Fiordland on the west.
Figure 60 A grove of nikau palms (Rhopalostylis sapida) growing near the sea at 42°S on the west coast of the South Island south of Westport.
Photo: J. W. Dawson.
Several other species also contribute to the canopy. Puriri (Vitex lucens), which has strong tropical affinities, is limited to the northern half of the North Island; tanekaha or celery pine (Phyllocladus trichomanoides) and black maire (Nestegis cunninghamii) reach the northern South Island.60 Hinau (Elaeocarpus dentatus) reaches the central South Island, while its higher altitude relative pokaka (E. hookerianus) reaches Stewart Island.
On the west and south of the South Island southern rata (Metrosideros umbellata) contributes to the canopy of kamahi forests.
Two species of decidedly tropical aspect reach the northern South Island, although they are never far from the sea in the southern parts of their ranges. These are kohekohe (Dysoxylum spectabile) with its large, pinnately compound leaves and our sole native species of palm the nikau (Rhopalostylis sapida)61 (Fig. 60).
A few other small trees prefer higher altitudes in northern New Zealand and they include broadleaf (Griselinia littoralis) and the mountain cabbage tree (Cordyline indirisa). The latter with its unbranched trunk and massive head of broad, silvery-green leaves is certainly the most handsome of our cordylines (Fig. 61). It looks as if it would be at home on a tropical strand, so it seems strange that it should favour moister, cooler, montane forests.
Kawakawa (Macropiper excelsum) is a distinctive undershrub with heartshaped leaves and jointed stems. Kawakawa is sometimes called 'native pepper tree' because of its hot tasting leaves, and it is in fact related to the true pepper plant of Indonesia. It is also related to the similarly named kava plant of Fiji. Horopito (Pseudowintera axillaris) with its dark green shiny leaves has also been termed 'pepper tree' for the same reason, but it is not in fact related to kawakawa. It belongs to the Winteraceae, a family often considered to be the most primitive of the flowering plants.
Other common shrubs are the thin-leaved hangehange (Geniostoma rupestre), kanono (Coprosma grandifolia) and pate (Schefflera digkata) with its large palmately compound leaves. The tree fern, wheki (Dicksonia squarrosa), may also be common. It is notable for spreading by horizontal stems or rhizomes to form groves.
In better lit places five-finger (Pseudopanax arboreus) may occur. Its leaves are of similar form to those of pate but they have a thicker texture and are more coarsely toothed at the margins. Accompanying species may be the two common larger-leaved coprosmas both known as karamu: C. robusta and C. lucida, the bubbly-leaved ramarama (Lophomyrtus bullata), wharangi (Melicope ternata), the 'tree daisies' heketara (Olearia rani) and the familiar large-leaved rangiora (Brachyglottis repanda).
Among the undershrubs which occur at higher altitudes in the north page 104are mountain horopito (Pseudowintera colorata), often with an extremely attractive red or yellow leaf colouration; mountain five-finger (Pseudopanax colensoi)P. simplex, the tree fern Cyathea smithii and Coprosma foetidissima.
The coprosma is sometimes known as 'stinkwood' because the crushed leaves smell like rotten cabbage. Indeed the name of the genus is based on this species, 'copros' being latin for dung. Insult is added to injury with the species name, so that Coprosma foetidissima could be translated as 'stinking dung plant'. In fact very few of the many species of Coprosma have an unpleasant smell.
Alseuosmia pusilla is a small shrub which is often overlooked since it frequently grows with mountain horopito and looks very much like it. In the absence of flowers or berries the easiest way to tell them apart is to turn over the leaves — those of horopito are white, those of Alseuosmia pale green. It has been suggested that, as the peppery leaves of horopito are unpalatable to deer they may also have been unpalatable to moas.62 In that case moas, like many bush lovers today, may have passed Alseuosmia pusilla by. The genus Alseuosmia seems to specialise in such mimicry. I have seen a form of this genus in a forest near Kaitaia with round bullate (bubbly) leaves, and I took it at first to be the familiar ramarama (Lophomyrtus bullata).
The most abundant plants on the forest floor are ferns, but flowering plants may also be found. Many of the ferns belong to such widespread genera as Asplenium, Blechnum, Polystichum and the membranous leaved filmy ferns (Hymenophyllum and Trichomanes). The two species of Leptopteris, although larger than the filmy ferns and not related to them, have similar membranous leaves. The famous crepe fern (L. superba) favours moist, shady, cool situations and owes its attractively fluffy leaf texture to the ultimate leaf segments, which are set at right angles to the plane of the leaf (Fig. 62).
Among flowering plants, species of Astelia form large tussocks; the bush rice grass (Microlaena cvenacea) covers the ground in places and in season the flowers of species of such orchid genera as Corybas and Pterostylis make their appearance. In the north, moist shady banks may be completely covered by attractive mosaics of the reddish-purple tinted leaves of parataniwha (Elatostema rugosum) (Fig. 63).page 105