Cockayne. — Plant Geography of the Waimakariri. 125 



by cultivation mainly those species have firmly established 

 themselves which are specially fitted by their structure to the 

 environment. Thus, to choose two out of many examples, 

 Verbascuvi thaysus, a most tomentose plant, is abundantly 

 naturalised on many river-terraces (Kowai Eiver and Eiver 

 Porter, e.g.), and Lwpinus arhoreus-'' on the sand-dunes. Had 

 the numerous weeds arrived before the ground was prepared 

 for them by man they would have met with a much more 

 stubborn resistance in the undrained Phormiuvi swamps, 

 &e. Statements such as that by Wallace,! of white- 

 clover wiping out Phormnmi, should be accepted with great 

 caution. Such swamps even now possess few introduced 

 plants, and remain virtually intact.^ 



This eastern climatic region may be conveniently divided 

 into the following subregions : — 



(1.) The Lowland Region : This embraces the country 

 drained by the Waimakariri, on the Canterbury Plain, and 

 extends from the ocean to the foot of the ranges. It 

 varies in altitude from sea-level to 457 m. Here (except- 

 ing towards its western boundary) snow rarely lies for 

 more than twenty -four hours, usually melting as it falls. 

 The rainfall varies on an average from less than 25 in. on 

 the sand-dunes to more than 40 in. at 457 m. This last 

 estimate is a mere guess ; but it is a fact that that alti- 

 tude gets rain from both north-west and south-west which 

 never reaches the sea-coast, and that rainy days must also be 

 much more abuiadant. The north-west and south-west winds 

 have been already treated of. The former is much more fre- 

 quent in the western portion of this region, and often blows 

 there with great violence, while a steady east wind is being 

 experienced at the coast and for some miles inland. The rain 

 from the south-west coming in squalls often does not wet the 

 ground on the sheltered side of large plants, so the smaller 

 ones growing there remain quite dry. Frosts may occur during 

 any month except December, January, or February. After 

 rain the ground in most places dries very rapidly. The whole 

 of the region is exposed to the full blasts of the winds, except- 



* L. arboreus is furnished with exceedingly succulent stems, made 

 up of abundant water tissue. Its leaves also are hairy on the under- 

 surface, and they have the power of reducing the leaf-surface consider- 

 ably through the two upper sides of the lamina of each leaflet folding 

 together. The leaves exposed to the sun may thus be seen closed up, and 

 those in the shade open wide. 



t " On Darwinism." London, 1889, p. 28. 



I Every student of New Zealand plant geography should read care- 

 fully Mr. Cheeseman's very excellent paper, " The Naturalised Plants of 

 the Auckland Provincial District " (Trans. N.Z. Inst., vol. xv., 1882, 

 p. 268). He has gone into the subject of the spread of weeds at some 

 length, and come to some very just and well-considered conclusions. 



