348 Tra/>xorUo//s. 



but this latter we consider with Tansley (1909) an unsatisfactory class, 

 since, on the one hand, it is evidently very close to steppe, and, on the other, 

 its forms are often altogether artificial. 



The land-surface of the mountain steppe consists of hill-slopes ; river- 

 beds, sometimes lying deep below the general surface of the land ; high 

 river-terraces w^hose remarkably flat tops are old flood-plains, but whose 

 stony faces slope steeply to the river-bed beneath ; heaps of old morainic 

 matter with the surface crumpled and irregular ; roches moutonnees and 

 river and torrent fans. 



The surface soil is a soft silty clay, the loess or semi-loess already spoken 

 of, which is readily denuded, easily moved by the wind, and rapidly becomes 

 dried up. Beneath, the clay may be stiff er, and there is nearly always a 

 porous gravelly and shingly subsoil which frequently comes close to the 

 surface. 



(2.) Siiccession. 



So far as our observations go, steppe has originated in the following 

 ways : — 



(a.) Through occupation of actual river-bed. a form of succession easily 

 studied at the present time. 



(/3.) Through disintegration of rock followed either by shingle-slip or by 

 a fan at the mouth of a river or torrent. 



(y.) Through occupation of moraine, boulder-clay, or other stranded 

 glacial debris. 



(8.) Through soil blowing on to a rock-surface which by degrees becomes 

 occupied by plants, these further trapping and holding fresh blown soil. 



(e.) Through a shallow lake being turned by various stages into dry 

 land. 



(3.) The Associations. 



(a.) Kock. 



Unfortunately our notes contain but little regarding the rock-vegetation ; 

 in fact, rock-faces are much less in evidence in the steppe belt than in that 

 of shingle-slip and fell-field. The rock-plants, leaving a niunber of mosses 

 and lichens on one side, are generally species also belonging to the steppe 

 proper, and their numbers depend altogether upon the form of the rock- 

 surface and its capacity for catching blown soil and accumulating humus. 



Asplenium Eichardi, a fern 5-12 cm. tall, with dark-green rather thick 

 much-cut tufted leaves given off from a short stout rounded caudex, is 

 abundant in shaded hollows of the rock. Tussocks of the grass Poa caespi- 

 tosa and Festuca nihra var. are common, even where there is little soil. The 

 small succulent herb Crassula Sieberiana is abundant, and the follow- 

 ing are also common : Danihonia semiannularis (tufted grass with slender 

 involute leaves), Muehlenbeckia axillaris (creeping, prostrate, wiry stemmed, 

 small-leaved shrub), Cardamine heterophi/Ua (annual herb 10 cm. or less 

 tall with slender decumbent stems and short moderately thick smooth 

 pinnate leaves), (kcalis corniculata (prostrate creeping herb with slender 

 matted stems and very small rather thick leaves), Epilobium pubens (semi- 

 erect herb wath stems suffruticose at base and pubescent leaves about 2-5 cm. 

 long and red beneath), Anisotome aromatica (rosette herb with very long 

 fleshy root and moderately thick pinnate linear leaves flattened to rock), 

 Raoulia australis (low cushion plant with much-rooting stems and small 

 close tomentose silvery leaves), Crepis novae-zelandiac (rosette herb with 



