15 



The vegetation, too, north of lat. 38deg. S., right to the 

 North of the North Island is distinguished by certain distinct 

 plant-associations, of which the most striking are Kauri (Aga- 

 this) forest (see Fig. 7) mangrove (Avicennia) salt-swamp the 

 shrub and bog associations of the barren clay gumlands, and the 

 pohutakawa (Metrosideros tomentosa) association of sea-cliffs. 

 Coastal forest, coastal scrub and stable dune associations are also 

 of a special character. Natural grassland is absent, its place 

 being occupied by shrubland. 



(4) LATITUDE 42S. AS A PHYTOGEOGRAPHICAL BARRIER. 



In the following list North Island species which extend to 

 Banks Peninsula on the east and beyond the Taramakau River 

 on the west are excluded. On the other hand, species which 

 have, so far, been recorded only from the extreme northern parts 

 of the South Island are included. The phytogeographical divid- 

 ing-belt is therefore of considerable width. The list given below 

 emphasises what has been already stated concerning the close 

 relationship between the adjacent lowland and coastal floras of 

 the North and South Islands. The following is the list of 

 species: (Filices) Adiantum aethiopicum, A, hispidulum, Pel- 

 laea falcata, Pteris tremula, P. macilenta, Blechnum filiforme, B. 

 Fraseri, Doodia media, Asplenium umbrosum, Arthropteris 

 tenella, Poly podium dictyopteris; (Lycopodiaceae) Lycopodium 

 cernuum; (Taxaceae) Phyllocladus trichomanoides ; (Gram- 

 ineae) Spinifex hirsutus, Dichelachne sciurea, POOL anceps var. 

 elata, Bromus arenarius, Agropyron multiflorum; (Cyperaceae) 

 Elaeocharis neo-zelandica, Schoenus brevifolius, S. tendo, 

 Cladium capillaceum, Gahnia setifolia, G. pauciflora, G. 

 xanthocarpa; (Liliaceae) Astelia Banksii, A. Solandri, A. triner- 

 via, Arthropodium cirratum; (Orchidaceae) 16 Prasophyllum 

 rufum, Pterostylis trullifolia, P. puberula, Acianthus Sinclairii, 

 Calochilus paludosus, Corysanthes Cheesemanii; (Piperaceae) 

 Peperomia Urvilleana; (Proteaceae) Knightia excelsa; (Poly- 

 gonaceae) Muehlenbeckia Astoni; (Magnoliaceae) Drimys 

 axillaris; (Monimiaceae) Laurelia novae-zelandiae ; (Lauraceae) 

 Beilschmiedia tawa; (Cruciferae) Lepidium incisum; (Pittos- 

 poraceae) Pittosporum corni folium; (Leguminosae) Car- 

 michaelia australis, C. odorata; (Rutaceae) Melicope ternata, 

 x M. Mantellii; (Meliaceae) Dysoxylum spectabile; (Tiliaceae) 

 Entelea arborescens; (Malvaceae) Hibiscus trionum; (Viola- 

 ceae) Hymenanthera obovata 17 ; (Thymelaeaceae) Pimelealon- 

 giflora; (Myrtaceae) Metrosideros Parkinsonii 1 8 , M. Colensoi, 



!6. Some of these orchids may extend much further south on the west of the 

 South Island since the orchid florula of the Western Botanical District is com- 

 paratively unknown. Mr. W. Townson collected orchids most assiduously in the 

 neighbourhood of Westport, hence the number of species recorded. So, too, for 

 the neighbourhood of Kaitaia (Northern Auckland), thanks to the labours of the 

 late Mr. R. H. Matthews and Mr. H. Carse. 



17 - Excluding from the conception of the species the Castle Hill (Canterbury) 

 plant. 



l g - Recently discovered by W. R. B. Oliver on Great Barrier Island its only 

 gtation north of Cook Strait, so far as is known. 



