116 Transactions. — Botany. 



fleurs des plus fines et des plus delicates, dignes au plus haut 

 degre d eveiller, notre attention et notre sympathie." 



Climatic Regions and Plant-formations. 



It is well known that many plants are accustomed to grow 

 in coniiDany with other plants, and that such communities, or 

 plant-formations as they are often called, occur again and 

 again in different parts of a district without their constituents 

 varying to any great degree. Thus a forest having Fagus 

 cliffortioides as its dominant tree may be expected to contain 

 certain other definite plants as undei'growth, while on the 

 trunks of the trees themselves the same mosses and lichens 

 will usually be found. If a portion of such forest be examined 

 in any part of a particular district, noting carefully its plant- 

 members and their relative frequency, it will be found that 

 such a forest will be typical of all others of that class, and 

 that if any marked change occur it will be in a region of 

 considerable difference in climate, soil, or altitude. Again, a 

 stony river-bed will carry certain plants, and such a station, 

 subject to the provisos indicated above, wull have the same 

 vegetation, no matter in what part of a district it may occur. 

 Into groups such as these may the flora of a region be divided, 

 and so the relations of each group of plants as a whole with 

 regard to moisture, soil, light, heat, air, and animals be con- 

 veniently studied, and the resultant life-forms of the com- 

 ponent species noted and considered. 



From the foregoing it must not be imagined that a plant- 

 formation is something definite and invariable ; on the con- 

 trary, hard-and-fast distinctions cannot be made. Transitions 

 occur between most ; certain plants enter into a formation in 

 one place which are entirely absent in another, or a plant 

 may have crept in which does not belong to the formation at 

 all. Thus in the Fagus formation near Arthur's Pass occurs 

 a solitary example of Olearia lacimosa, a plant really belonging 

 to the upper limits of the Westland forest, or sometimes form- 

 ing a small percentage of the subalpine scrub of that region. 

 Nevertheless, this classifying the plants of any district into 

 communities which resemble one another so much in their 

 adaptations to their environment that they usually grow^ 

 together is well fitted for the object aimed at — viz., a study 

 of such adaptations — while also from the floristic point of view 

 it is a concise method of mapping the vegetation. 



One great difficulty is to properly estimate the effect of the 

 various external factors on plant-life, and statements must 

 necessarily be often based on very uncertain and incomplete 

 observations, especially so indeed in a "new country," where 

 even the most general details as to temperature, composition 

 of soil, rainfall, &c., are not accurately known. Two factors 



