220 SUBANTARCTIC ISLANDS OF NEW ZEALAND. [Ecological Botany. 



separating these " lanes," where examined, were in straight belts 4 m. or 5 m. wide, 

 and parallel to the direction of the prevailing wind. A " lane " would be about 

 12 ni. across, and its vegetation consist of Danthonia antarctica tussocks, cushions of 

 Oreobolus pectinaius, mats of Coprostna repens and Styphdia empetrifolia, and other 

 meadow plants. Down the " lane " the full violence of the wind can be felt. 



It is not easy to accoimt for the presence of these " lanes." Perhaps they are 

 the remains of Danthonia meadow in process of invasion by rata forest. Thus, let a 

 rata bush once become established, then on its leeward side another individual could 

 gain a footing, and so on until long files parallel to the wind result. But between 

 these the hemmed-in wind will have redoubled power, and the capture of a " lane " 

 by trees be a very slow and uncertain process.* Juvenile rata-trees occur in fair 

 abundance in these grassy openings, and it looks as if they finally would change 

 into forest.f 



(viii.) Pleurophyllum Hookeri Formation (fig. 13). 



Near the summits of the hills, in sopping wet though frequently stony ground, 

 is a plant formation of a more or less open character, made up of many species which 

 grow close to the surface of the ground. First and foremost, and giving a most 

 striking appearance to the landscape, come the silvery-green rosettes of Pleurophyllum 

 Hookeri, which may be solitary or several together from a branching stem. Fre- 

 quently the plants grow closely together, and many square metres glisten with the 

 silvery covering. Generally Carpha alpina mixed with Astelia linearis forms the 

 groundwork of the formation, or in other places this may be the filmy fern 

 Hyrnenophyllum multifidum, its fronds closely curled, and reddish or brown in 

 colour. In some places the glistening green mats of Celmisia vernicosa are as 

 numerous as the plants of P. Hookeri. Veronica Benthami, and the two cushion 

 plants Oreobolus pectinatus and Gaimardia ciliata are extremely common. Every- 

 where are the arching, rather large green leaves tinged with brown of patches of 

 Bulbindla Rossii. Where the groimd is especially stony, right under the rocky 

 summits, are quantities of the green rosettes of broad leaves of Plantago aucklandica. 

 Also, this is the especial station of the small and most common form of Ranunculus 

 pinguis, the diameter (2 cm.) of the glistening canary-yellow subsessile flower being 

 out of all proportion to the size of the small rosettes (3-2 cm. diameter) of moderately 

 dark-green glossy leaves flattened to the ground. Very abundant, too, is Myosotis 

 capitata, with perhaps the most lovely flower of the islands, its blossoms a brilliant 

 dark blue, 5 or so crowded into a head 2-1 cm. broad, and each about 11 mm. in 

 diameter. Noteworthy on the stony ground in some places is Cardamine glacialis 

 var. svbcarnosa,X its small dark-green rather fleshy pinnate leaves in rosettes, each 

 7 cm. in diameter, given off from a rather stout rootstock, and its root penetrating 

 very deeply. 



* Such a condition of affairs would be analogous to the wind-channels of a dune area, where 

 without shelter it is impossible to estabhsh even sand-binding grasses. (Cockayne, L., " Report on 

 Sand Dunes of New Zealand," 1909.) 



t Since I wrote the above Professor C. Chilton has called my attention to J. E. S. Moore's explana- 

 tion of certain African " park " lands (" To the Mountains of the Moon " ; fig. p. 4, and p. 320-326), 

 where a desert xerophyte {Euphorbia) encourages plants of more mesophytic structure to settle in its 

 shade, just as does the wind-tolerating M. lucida allow settlement in its lee. 



X This is the only plant analogous to those of shingle slips in the Southern Alps. 



