172 Transactions. 



V. buxifolia, as another variety with erect and. but little-branched stems, 

 forms low thicket in wet subalpine western stations, and the two associa- 

 tions must not be confused. 



Besides the shrubs there are certain ground-plants in the scrub under 

 consideration. Without giving a special list, the following are character- 

 istic : Cystopteris novae-zealandiae, Blechnum perma marina, Polystichum 

 vestitum, Lycopdium fastigiatum, Acaena Sanguisorbae var. pusilla and var. 

 pilosa, Epilobium pnhens, and, if the floor is not too dry, E. chloraefolium. 



The lianes of the scrub are : Muehlenbeckia complexa var., Clematis 

 australis, C. marata, Ruhus schmidelioides var. coloratus, and R. sub- 

 pawperatus. 



On Mount Sugarloaf there is the interesting open shrub association 

 already referred to growing on a slope of unstable debris, the chief 

 characteristic of which is the dominance of the common prostrate variety 

 of Podocarpus nivalis, forming broad patches, orange-brown in colour, 

 which may grow into one another. The above colour is not perma- 

 nent, but depends upon the direct action of the sun. Here and there 

 are the erect bushy shrubs of another variety of Podocarpus nivalis, 

 some of which are 1-8 m. high, and 1-2-1-5 m. through (see Plate XV, 

 fig. 2). Other shrubs present are : Clematis australis prostrate on the 

 stones, Hymenanthera dentata var. alpina, Aristotelia fruticosa, Lepto- 

 spennum scoparium var., Gaultheria rupestris var., Dracophylluni longifolium 

 (stunted), Styphelia Colensoi, S. Fraseri, Pimelea Traversii, Coprosma pro- 

 pinqua var. Various herbs, &c., occur on the open spaces between the 

 patches of P. nivalis — e.g., Asplenittm Richardi, Blechnum pemia marina, 

 Lycopodium fastigiatum, Poa sclerophylla (on the finest debris), P. Colensoi 

 var., Ejnlobium piibens, Myosotis australis var., Celmisia spectabilis, C. 

 Lyallii, Senecio lautus var. 7)iontanus. Ecologically the association belongs 

 rather to fell -field than to shrubland, while the finer debris bears true 

 shingle-slip plants. 



(3.) Lovf Tussock Grassland.* 



" Tussock grassland" is here used as a substitute for the term "tussock 

 steppe " hitherto used by L. Cockayne in his ecological publications. The 

 reasons for abandoning the word " steppe " have already been given. All 

 the same, when attention is called to the effect of overstocking and burning 

 in increasing the percentage of bare ground to that clothed by tussock, &c., 

 until, as in Central Otago, desert pure and simple is established, there is 

 certainly an induced steppe association in New Zealand, just as there is 

 induced desert. Such induced steppe, however, we would now term " open 

 low tussock grassland," a term having the merit of defining itself. 



The word " low " before " tussock " indicates that the tussocks are 

 either Poa caespitosa or Festuca novae-zealandiae, and not the much taller 

 tussocks Danthonia Raoidii or D. flavescens, which, when dominant, one 

 or the other, make "tall tussock grassland," a formation absent in the 

 immediate vicinity of Cass. 



Low tussock grassland is far and away the most important association 

 in the vicinity of Cass — ^as, indeed, it is for the whole of the South Island of 

 New Zealand east of the actual divide. Its presence is clearly in harmony 

 with the drier eastern climate, and when the average rainfall and number 



* The paper by A. H. Cockayne in this same volume (pp. 154-65) should be read in 

 conjunction with this section of o\ir paper, since it opens up and discusses many matters 

 of phytogeographical interest which we have not touched upon. 



