Speight, CockayxI':, Laino. . — 3/oinif Arroirx/nif/i Dixfrirl. 343- 



mentioned in the same work. Haast (1866) noted a few of the plants of 

 Browning's Pass, and calls attention to the subalpine scrub on Main's 

 Knob, describing his passage through it as " a herculean task." Mr. J. B. 

 Armstrong (1879) described several new species from material collected 

 by Mr. J. F. Armstrong, who, with the late Mr. W. Gray, of Governor's Ba}', 

 had made an excursion to the Kangitata Valley in 1869. These species 

 were, for the most part, again described by J. B. Armstrong in the " Trans- 

 actions of the New Zealand Institute" (1881). Mr. R. Brown, of Christ- 

 church, accompanied by Mr. F. N. Adams, botanized in the Wilberforce 

 Valley in 1885, following the Moa Creek to its source. A popular account 

 of the excursion was written by the latter, enumerating some of the plants 

 met with — e.g., HymenophyUmn Mallingii, Alsophila Colensoi, Polystichum 

 eystotegia, Baminculus Godleyanus (abundant), Veronica macrantha (Adams. 

 1885). Lihocedrus BidwiUn is stated to be the leading forest-tree. Brown 

 published his results later (1894, 1895, 1899), describing several new species 

 of mosses. During the progress of 'the present geological survey of New 

 Zealand a few plants were collected in the vicinity of Browning's Pass^ 

 and these, identified by Mr. A. H. Cockayne, are published in the report 

 dealing with the " Hokitika Sheet " (Bell and Fraser 1906, p. 101). 



The authors visited the Arrowsmith district in the summer of 1909-10, 

 but independently of one another, and at different times. Laing examined 

 the vegetation of Mount Potts and the adjacent parts of the Rangi- 

 tata and Clyde Valleys, and also the Cameron Valley to its glacier ; 

 Cockayne, who had the special advantage of Mr. R. Speight's company 

 and geological knowledge, paid attention to the country in the vicinity 

 of Lake Heron, and thence to the neighbourhood of Mein's Knob, on the 

 south side of the River Rakaia, opposite the terminal face of the Ramsay 

 Glacier, and for the account of the associations, &c., of that part of the 

 district he is alone responsible. Both authors studied the plant covering 

 of the lower Ashburton Gorge, and the upper Ashburton Plain as far as the 

 stony bed of the River Cameron. Only a few weeks were spent on the 

 work, even when both excursions are considered. It is plain, therefore, 

 that but a very superficial knowledge of the district was gained, and were 

 it not that matters of general interest are discussed, and formations con- 

 sidered, which concern also other river-valleys of eastern Canterbury, .&c., 

 with which we are better acquainted, and which also belong to the glaciated 

 area, this paper would not have appeared. 



The term " Arrowsmith district " is used in a broad sense. It includes 

 not merely the actual range itself, but portions of the adjacent country, 

 including the momitains lying to the east and north of the upper Ashburton 

 Plain ; but its topography and geology is sufficiently described in Part I. 

 It must, however, be pointed out that the word " district " is not used in 

 its phytogeographical sense, the area dealt wath including, in point of fact, 

 portions of two botanical districts. 



2. PRIMARY CAUSES AFFECTING THE CHARACTER AND DISTRIBUTION 

 OF THE VEGETATION. 



(A.) The Glacial Period. 



All authorities agree that the present glaciers, extensive though they 

 are, represent a fraction merely of their former area ; the only point in 

 dispute is as to how far they extended into the lov\'er country. But with 

 regard to phytogeography the extent of the glaciation matters little, so long 



