Rhipogonum scandens, particularly in the lower three-quarters of the belt, often forms practically impenetrable tangles, and the shade underneath them is so complete that the floor is almost devoid of shrubby or herbaceous plants, and even bryophytes are scanty. Freycinetia Banksii also abounds, climbing by roots and heavily festooning trees with its long tufted foliage. Where sufficient light reaches the floor, especially on steep faces, it spreads in a dense entanglement, the heads rising 1–2 m. from the ground. Of other high climbers, Metrosideros scandens, Clematis indivisa, and to some extent Rubus cissoides also occur. In a lower tier, together with numerous young trees of the higher tiers, Myrtus pedunculata in dry stations and Schefflera digitata in wet are usually found, while with increase in altitude Pseudowintera axillaris and Senecio Kirkii, the latter at lower altitudes more usually epiphytic, come in. On the forest floor itself, forming a tier 1 m. in height, the following are abundant, one species now and again becoming dominant:—Microlaena avenacea, Gleichenia Cunninghamii, Blechnum discolor, Polystichum Richardi, Asplenium lucidum and Uncinia riparia. Astelia Cunninghamii, Asplenium bulbiferum and Alseuosmia macrophylla also occur frequently in places.

The ground, decaying logs, trunks and branches of trees and even shrubs are more or less clad with filmy ferns, mosses and liverworts. Large areas of more or less pure Cardiomanes reniforme are common, and the following are also plentifully distributed:—Hymenophyllum dilatatum, H. sanguinolentum, H. biforme, H. demissum, while H. tunbridgense, Polypodium Billardieri, Trichomanes venosum are frequently present. Where more light can penetrate Lindsaya cuneata and Histiopteris incisa are common.

Perched on the canopy trees the following epiphytes are common: Astelia Solandri, Dendrobium Cunninghamii, Earina autumnalis, E. mucronata, Asplenium flaccidum and Tmesipteris tannensis.

The following species are common on the outskirts of the forest where the primitive covering has been broken in the course of settlement: Pteridium aquilinum esculentum, sometimes dominating limited areas, the climbers, Muehlenbeckia complexa and Metrosideros perforata and in clearings Lagenophora pumila and L. petiolata.

The warm temperate forest of the Northern Tararua Area is chiefly noteworthy for the absence, from about Mount Mairakau northward, of Nothofagus fusca, which is elsewhere plentiful, and for the presence in abundance of Mida salicifolia, and Macropiper excelsum, while in the vicinity of the Manawatu Gorge Myoporum laetum and Melicope simplex are common. In the Mangahao valley, Nothofagus Menziesii, which further south is mainly confined to the cold temperate belt, descends into the warm belt in appreciable quantity. The Mangatainoka and Ruamahanga valleys also present some peculiarities of vertical distribution, which are dealt with in the ecological section of this paper under local climatic variations.

In the Eastern Tararua Area Nothofagus fusca dominates the climax association. Weinmannia racemosa is abundant in a lower tier, and the undergrowth, which is very open, is mainly composed of Cyathea Smithii, Coprosma Banksii, Cyathodes acerosa, Leuco-

pogon fasciculatus, and Coprosma rhamnoides with some Rhipogonum scandens and Freycinetia Banksii. The floor is thickly covered with dry leaves of Nothofagus and Weinmannia. The most conspicuous filmy fern is Cardiomanes reniforme, which often covers large patches of ground. In some places, particularly where the ground is level, Blechnum discolor is plentiful. The bryophyte representation is poor.

In the Southern Tararua Area most of the lowland forest has disappeared. What is left, being fairly close to the sea, shows in several places traces of an admixture of coastal species. In the Muka-muka basin and on the western flank of the area Corynocarpus laevigata, Myoporum laetum and Melicope ternata are common, while on the west side in addition Dysoxylum spectabilis is plentiful. Apart from these areas, the dominant tree of the climax association appears to be Nothofagus truncata, co-dominant perhaps in some places with N. Solandri, the general aspect of the association resembling that of the Eastern Area, but the following additional species are common: Danthonia flavescens Cheesemanii, Pittosporum tenuifolium, Macropiper excelsum and Melicope simplex. Knightia excelsa and Podocarpus spicatus are also prominent, the latter dominating a local area in the Wairongomai valley.

Warm Temperate Belt: Watercourse, Riverbank, and Cliff.

The watercourse and riverbank formation is essentially younger in succession than the forest which it traverses and differs from it in two ways. Light is freely admitted to much lower levels, so that shrubby and herbaceous species predominate. The perpetual high humidity gives the formation its abundance of bryophytes and pteridophytes. Throughout the whole of the Tararuas there are but slight differences in the associations since they are but little dependent directly on rainfall. The ground generally is densely covered by ferns and mosses and the branches of trees are densely festooned with species of Weymouthia. Wet banks are usually occupied by Gunnera strigosa, with some Gnaphalium keriense, Veronica catarractae (little on the western side), Pratia angulata and occasionally Ourisia macrophylla. Elatostema rugosum is characteristic of the Northern Area. Frequently Blechnum procerum forms pure colonies of considerable area, attaining its maximum development on steep sheltered slopes. Of the taller shrubs Fuchsia excorticata, Schefflera digitata, Aristotelia serrata, young Melicytus ramiflorus, Coprosma australis, and, in better-lit situations, Brachyglottis repanda and Hebe salicifolia—the latter with several recognisable varieties occupying separate more or less defined areas—are most common. Of climbing plants Rhipogonum scandens and Freycinetia Banksii are often present and Muehlenbeckia australis, Parsonsia heterophylla and Rubus cissoides are not uncommon in the lowlands.

On the more exposed banks, and particularly in rocky gorges, Carmichaelia odorata is generally plentiful, and with increasing exposure Phormium Colensoi may make its appearance. Of ferns Adiantum affine and Polypodium grammitidis are common in rocky stations.