212 Transactions. — Botany. 



The influence of temperature, liowever, in producing a luxuriant plant-growth. 

 is of less importance than humidity, whether derived from the normal humid 

 condition of the prevailing winds, or locally by the evaporation from swamp 

 lands or the cover of bush. The amount of humidity present in the atmosphere 

 differs much in different districts, and can be easily known without the aid of 

 meteorological instruments by the greater or less abundance of those low forms 

 of vegetable life — the lichen-fungi — whose minute forms often give a colouring 

 to rocks and bark of trees. They are seldom found where dry winds prevail, 

 but often in great profusion on the coast line, and inland for several mUes, and 

 at altitudes on the hills where rain-clouds hang. The normal condition of the sea- 

 winds at Wellington is humid, but for short pex'iods cold arid winds accompanied 

 by rain prevail, whose blighting influence on some plants, especially those 

 with membranaceous leaves, or tender introduced species, is almost destructive, 

 and, but for the shelter of more robust species, many (such as Piper excelsum) 

 would become extinct. This blighting influence of the sea-winds has been 

 erroneously ascribed to the presence of salt carried from the ocean ; but if 

 this were the case every storm should produce the same blighting effect, 

 whereas it occurs seldom more than once or twice in a year, and only for a 

 few hours. 



For convenience the flora of Wellington will be arranged under five natural 

 divisions : bush, open land, alpine, littoral, and marine. From the equability 

 of the climate, the species of the first and second divisions are very uniformly 

 distributed over their own areas up to 2,000 feet. It is presumed, therefore, 

 that any artificial system of zones of altitudinal distribution in a district where 

 the greatest altitudes are only 5,000 feet would fail in correctness, as it has 

 been already shown that the selection of habitat by species within this limit is 

 more influenced by soil than temperature. 



The geographical position of the timber trees is a subject of much 

 importance in a commercial point of view. As the country is opened up by 

 railroads it will be found that the species easiest reached differ in different 

 districts, both in kind and value. The value of any timber being pi-oportionate 

 to its strength and durability for constructive or other works, these qualities 

 again are entirely ruled by the kind of soil and the amount of exposure under 

 which it is grown. For it is an erroneous idea that if once some particular 

 kind of tree, such as totara, has produced durable timber, all totara will be 

 durable ; for that which is grown on rich alluvial sheltered bottoms will, 

 undoubtedly, be inferior in durability to that which is grown on exposed hill- 

 ridges, the growth of the latter being much slower, producing a timber of 

 greater specific gravity and containing more secreted oil. So, also, does soil 

 and exposure influence the strength of those timbers which are selected for 

 building purposes (such as rimu), where capacity to resist transverse strain is 



