Ecological Botany.] SUBANTARCTIC ISLANDS OF NEW ZEALAND. 209 



the floor is bare, except for dead leaves and branches and occasional patches of 

 seedlings. Usually there is no undergrowth, unless in the bottom of a gully, where 

 there will be a few plants of the dark-green ferns Polystichum vestitum and Blechnum 

 durum. Senecio Stewartiae has much the same habit as the Olearia, but its leaves 

 are bright green, and so break the monotone of the formation ; but it becomes a 

 still more striking feature when in December and January it is loaded with its great 

 panicles of golden flower-heads. 



(ii.) Meadow Formations {Tussock Meadow). 



There are two distinct meadow formations, one where Poa foliosa and the other 

 where P. litorosa is dominant. Warming (" Oecology of Plants," pp. 199, 200 ; 

 1909) points out that these subantarctic tussock formations differ widely from and 

 cannot be grouped with any of the Northern Hemisphere. 



* Poa foliosa Mead^rw. 



This formation stands out conspicuously through its bright-green colour. The 

 grass has the tussock form ; the plants grow so closely as to make a closed formation, 

 and the broad leaves droop somewhat. Stilhocarpa robusta* grows occasionally as 

 an isolated specimen, but in other places there are broad patches, mixed perhaps, 

 but sparingly, with the ferns Asplenium ohtusatum and Blechnum durum. The 

 darker green of the large orbicular leaves contrasts with the paler and brighter- 

 coloured grass. Its stout rhizomes, when once it can gain a foothold, give it an 

 advantage over the competing plants. 



This formation, either pure grass or grass with the Stilbocarpa, occupies the 

 hollows and sheltered places, but where the westerly wind strikes with full power 

 it is replaced by Poa litorosa, a grass of stronger xerophytic structure and life form. 



** Poa litorosa Meadow. 



This formation is browner in colour than the last described. The plants are 

 rounded, close-headed tussocks growing on trunks 57 cm. or more tall, the heads of 

 filiform involute leaves touching, and bare ground between the trunks. The leaves 

 are erect and extremely dense, and their withered extremities give the formation 

 as a whole a yellowish-green colour. 



The endemic Stilbocarpa robusta also grows in this formation to some extent, 

 but its real station is in sheltered spots, where it luxuriates, forming an almost pure 

 growth many square metres in extent. 



(iii.) Coastal Formations. 



On the rocks are many vivid-green cushions of Colobanthus muscoides, some 

 quite 41 cm. in diameter and 5 cm. or 6 cm. high, but the greater number much 





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* For this very distinct species, which bears but little resemblance to S. LyaUii, of which Kirk made 

 it the variety robusta, I proposed while on the Snares the name of Bollonsii, as a small tribute to what 

 the expedition owed to the enthusiastic captain of the " Hinemoa," Captain J. BoUons. This manu- 

 script name has already been used in England (W. Watson, " Gardeners' Chronicle," vol. xlv, p. 2), 

 but in accordance with the rules of the Vienna Congress I am here calling it S. robusta. In general 

 habit and appearance it resembles S. polaris, never increasing by means of runners like S. Lyallii. 



14-S. 



