23 



With regard to special edaphic examples three cases stand 

 out clearly the associations of soil with excess of salt, the 

 vegetation of ground near fumaroles and the magnesian soil of 

 the Mineral Belt. 



The leading salt-soil associations are salt-swamp, salt- 

 meadow, peaty salt-meadow (coastal moor), rocks exposed to. 

 sea-spray and salty patches in dry inland areas. The coastal 

 salt-associations consist of a small florula which extends with 

 but few changes throughout the three islands. A few of the 

 species are confined to salt ground, but most grow equally well 

 in non-saline stations, and some of these, which are character- 

 istic halophytes, extend inland, far from the sea, (e.g., Eryngium 

 vesiculosum, Leptocarpus simplex, Selliera radicans). 



The association near hot-springs on the Volcanic Plateau is 

 shrubland with, as so frequently, Leptospermum ericoides domin- 

 ant. According to the amount of sulphur fumes and the excess 

 of certain salts, etc., in the soil, so do the species gradually 

 decrease until only Lycopodium cernuum, Leptospermum 

 ericoides (now prostrate) and Leucopogon fasciculatus (still 

 erect) remain. 



The Mineral Belt is a narrow girdle of serpentine and 

 peridotite rocks, which in places crop out and in others lie as 

 debris, large and small, upon the surface-soil. It extends from 

 D'Urville Island to the Dun Mountain and beyond. It can be 

 recognised at a glance, and from a long distance, by its scanty, 

 stunted vegetation standing distinct from the adjacent forests. 

 So soon as the magnesian soil is encountered at its full strength 

 the neighbouring forest giv -s place all at once to shrubland or 

 tall tussock-grassland (see Fig. 10). Most of the species are 

 common New Zealand plants; but, if trees of the adjacent 

 forest, on the Mineral Belt are dwarfed at once to shrubs (e.g., 

 the species of Nothofagus, Griselinia littoralis). The species 

 Myosotis Monroi and Pimelea Suteri are local endemics. The 

 rare species Notothlaspi australis and Colobanthus quitensis 

 are common. Many of the shrubs are pronounced xerophytes. 



4._CONTINUOUS AND DISCONTINUOUS DISTRIBUTION. 



The fact that species are arranged in associations most 

 diverse in character postulates the impossibility of the really 

 continuous distribution of any species. Continuity can only 

 mean that the associations in which the species in question 

 occurs extend for a longer or shorter distance, either latitudinally 

 or vertically, with breaks between. Species belonging to wide- 

 spread formations (e.g., dune, salt-swamp, salt-meadow, forest, 

 tussock-grassland, Leptospermum shrubland, Pteridium heath, 

 stony river-bed) may extend for long distances. Thus Scirpus 

 frondosus (dune), Leptocarpus simplex (salt-swamp), Selliera 

 radicans (salt-meadow), Dacrydium cupressinum (forest), Poa 

 caespitosa (tussock-grassland), Leptospermum scoparium 

 (shrubland), and Pteridium esculentum (heath) afford common 

 examples of continuous distribution. But these species (Poa, 



