CHAP. XLVii GRASS-HEATH. TUSSOCK-FORMATION 199 



DISTRIBUTION 



Low-moor occurs on the most widely-separated parts of the Earth, 

 even in Arctic countries for instance, on the White Sea.^ Stages transi- 

 tional between it and swamp-bushland or swamp-forest often present 

 themselves. We may cite, for instance, a form of swamp-meadow in 

 Servda described by Adamovicz - : here associations are formed by Salix 

 pentandra, and Betula pubescens, which never attain man's height and 

 are richly branched from the base. Between these shrubs appear smaller 

 groups of Phragmites and Typha latifoha, and in the vegetation clothing 

 the ground are Calamagrostis lanceolata, Avena rufescens, Cirsium 

 palustre, Succisa pratensis, Caltha palustris, Trollius europaeus, Pole- 

 monium caeruleum, and others. 



CHAPTER XLVIII. GRASS-HEATH. TUSSOCK-FORMATION 



The formations on acid humus are allied to divers plant-communities 

 which most probably should be regarded as separate formations, but 

 have been inadequately studied. Among such we may include those 

 mentioned below, which show a preponderance of grasses, but apart 

 from this exhibit great differences among themselves. 



Grass-heath occurs in northern Europe, and Grabner ^ alludes to its 

 presence in northern Germany. In the Alps the setaceous-grass meadow 

 represents this formation and covers vast areas. It occurs on all kinds 

 of soil, calcareous or primitive, where the soil is dry and shallow, and 

 where the slope is not too steep to permit of the accumulation of raw humus. 

 The dominant species are Nardus stricta, Mohnia caerulea, Carex montana, 

 Agrostis alba, and Anthoxanthum odoratum. In addition, Cladonia and 

 Calluna may lodge here and there.* Similar nardeta occur in Ireland ^ 

 and Denmark.^ 



Tussock-formation. Differing widely from these grass-heaths are 

 the austral communities about to be described : 



The tussock- formation of New Zealand is described by Cockayne ' as 

 follows : ' The surface of the ground is very wet peat, in many places 

 being actual swamp. . . . The tussock meadow is by no means a uni- 

 form formation, but varies so much in composition and physiognomy 

 that ' it must be divided into various sub-formations. One of these is 



(fl) The maritime tussock slope. Here, ' From the steeply sloping 

 bank of soft, wet, and spongy peat rises up a dense mass of tussocks 

 about 1-5 metres in height, growing upon thick trunks so very closely 

 together that it is not easy to walk between them. These tussocks consist 

 chiefly of a species of grass ', probably Poa anceps. ' Mixed with this 

 tussock are others ... of Poa fohosa and Carex trifida.' 



{h) Flat tussock meadow. ' Perhaps this should rather be classed as 

 a heath . . .' ' The badly-drained soil, poor in nourishment, the abun- 



' Pohle, 1903. Adamovicz, 1898. ' Grabner, 1901. 



Kerner, 1863 ; Stebler und Schrotcr, 1889, 1892. 



Pethybridge and Praeger, 1905. 



Raunkiar, 1889; Warming, 1894, 1907-9- ' Cockayne, 1904. 



