Jay. 1911.] BOTANICAL SOCIETY OF EDINBURGH 105 
A New Zealand stony river-bed, such as is about to be 
described, also affords an excellent, though less known, 
subject for study, while in its case there is probably pro- 
ceeding before our eyes the same procession of events 
which culminated in the present steppe-vegetation of the 
stony river-formed lowland plains and flat valley floors of 
the higher land. That is to say, the peopling of a sub- 
alpine river-bed in the neighbourhood of the glacier-source 
of the stream may be a very similar phenomenon to what 
happened on the Canterbury Plains during their formation 
in the New Zealand glacial period. This statement does 
not imply that the species were then exactly the same as 
now,! but it assumes that similar growth-forms were then 
existent, and that these would behave as at the present 
time. 
The study has, moreover, an economic bearing, since, 
leaving the lowland plains out of the question, it deals with 
the evolution of the vegetation of those “ river-fiats ” which 
form some of the most valuable grazing-ground of the 
sheep-farmer, and it is clear how a knowledge of the 
methods by which Nature clothed them with nutritious 
grasses has a close bearing on any scheme dealing with 
their regeneration and improvement. 
The subalpine river-bed of the Rakaia has been selected 
for description, not only because it is typical of the glacier 
river-beds on the eastern side of the Southern Alps, but 
because I had an opportunity during the summer of 1909- 
10 of examining its vegetation in the light of observations 
made previously elsewhere. The portion studied was the 
southern side of the river almost opposite the terminal face 
of the Ramsey Glacier at about an altitude of 900 m. above 
sea-level, and where the valley is about 1 km. in width. 
The general aspect of the locality may be better judged 
from the fine photograph taken by my friend Mr. R. 
Speight, M.Se., F.G.S., to whom I am much indebted for 
many valuable suggestions while preparing this paper, than 
from any pen description (see Plate IX.). 
1 Raoulia Haastii is essentially a plant of forest-climate, and as the 
neighbourhood of the terminal faces of the great pleistocene glaciers 
would have, most likely, an extreme steppe-climate, the more xerophytic 
Raoulia species would be the pioneer plants. 
