Confined to New Zealand's North Island virtually all trees, shrubs and ferns in these forests are evergreen, but the general absence of bright green is said to give them a somber appearance. They are usually highly stratified with at least five tiers, and can generally be divided in four sub-associations distinguished by the dominance Agathis australis (Araucariaceae), Beilschmiedia taraire, B. tawa (Lauraceae) or the co-dominance of Laurelia novae-zelandiae (Monimiaceae) and Rhopalostylis sapida (Arecaceae).  All of these species are endemic to the New Zealand.  In the case Agathis australis (the Kauri)forest, this species is often very conspicuous because of its immense size, and keeps itself clear of epiphytes by shedding bark.  It is an extremely ancient plant dating back to the Jurassic period, and is the only New Zealand member of the Araucariaceae family. Other associated tall trees include the endemic Weinmannia sylvicola (Cunoniaceae). Tree ferns like the endemic Cyathea dealbata (Cyatheaceae) and Dicksonia lanata (Dicksoniaceae) are also very common, while another characteristic feature are dense tussock-thickets of the endemic sedge Gahnia xanthocarpa (Cyperaceae) and the endemic grass Astelia trinerva (Poaceae). Other endemic taxa include Alseuosmia banksii var. linariifolia (Alseuosmiaceae), Metrosideros albiflora (Myrtaceae), Mida salicifolia (Salicifolia)and Pittosporum primeleoides (Pittorsporaceae).

Beilschmiedia taraire forest is mainly confined to areas north of 36 degrees south. They have a fairly open appearance and commonly include Metrosideros robusta, which with its irregular trunks supports large numbers bryophytes and asteliads.  Other common trees include various podocarps such as Podocarpus ferrugineus and the endemic P. totara and Dacrydium cupressinum (Podocarpaceae) together withother endemic taxa like Dysoxylum spectabile (Meliaceae), Knightia excelsa (Proteaceae), and Phyllocladus trichomanoides (Phyllocladaceae), but much rarer are Dacrydium kirkii and the endemic Libocedrus plumosa (Cupressaceae). The undergrowth is rarely dense, but various low trees, shrubs and tree ferns occur such as Cyathea medularis, Suttonia australis and the endemic Alseuosmia macrophylla (Alseuosmiaceae), Pseudowinteria axillaris (Winteraceae)and Coprosma arborea (Rubiaceae). Fallen trunks are often thickly covered with endemic ferns like Hymenophyllum dilitatum with its translucentfronds, and the dark green Trichomanes reniforme (Hymenophyllaceae), while the forest floor includes other endemic ferns like Blechnum filiforme (Blechnaceae) and the vivid green Hymenophyllum demissum (Hymenophyllaceae).

Beilschmeidia tawa forest occurs mainly south of latitude 36, but much of this forest type has been destroyed. According to historical accounts the associated tree species included endemic taxa like Dacrydium cupressinum (Podocarpaceae), Elaeocarpus dentatus (Elaeocarpaceae), Litsaea calicaris (Lauraceae)and Pittospermum tenuifolium (Pittosporaceae) while species in the undergrowth would have included Myrtus bullata and the beautiful Senecio kirkii together with a great variety of ferns and bryophytes. This type of forest also occurs in montane areas where the monotypic endemic Ixerba brexioides (Ixerbaceae) can be found.

The Laurelia-Rhopalostylus association is confined to moist gullies. The endemic Rhopalostylus sapida (Areaceae) is the only member of the palm family found in New Zealand and appears to have established itself here during the Miocene epoch when there was much more of a tropical climate. It is usually trunkless and can dominate certain areas. Other characteristic species include Dryopteris pennigera and various endemics like Aspenium bulbiferum (Aspeniaceae), Dicksonia squarrosa (Dicksoniaceae)and Elatostema rugosa (Urticaceae).

References

Cockayne, L. 1958. The Vegetation of New Zealand. H. R. Engelmann (J. Cramer).

Molloy, L. 1994. Wild New Zealand. The MIT Press, Cambridge, Massachusetts.

Sohmer, S. H. 1990. Elements of Pacific phytodiversity. In: The Plant Diversity of Malesia. Proceedings of the Flora Malesiana Symposium commemorating Professor Dr. C. G. G. J. van Steenis Leiden, August 1989. Eds. P. Baas, K. Kalkman and R. Geesink. Kluwer Academic Publishers.