Plant Communities of the World 285 



especially by a Sphagnum covering. The climate is cool oceanic. 

 Moss moors have a wide distribution in Scandinavia, Great 

 Britain, Ireland, and in northwestern Germany in Europe. 

 Northern North America also has Hochmoor, and, in the 

 southern hemisphere, so do the Antarctic islands, Patagonia, 

 Tasmania, New Zealand. The habitat is peculiar. Osvald groups 

 these communities in Europe into four large types or federa- 

 tions — probably: (i) the western "ground covering," Eriopho- 

 rum vaginatum Hochmoor, in England, Scotland, and Ireland; 

 (2) the flat moss moor, Sphagnum rubellum Hochmoor, in 

 southwest Sweden, along the Norwegian west coast, in low alti- 

 tudes of the northern Scandinavian mountains, and in northern 

 Finland; (3) the truest moss moor, Sphagnum medium Hoch- 

 moor, in southern and central Sweden, southwestern Finland, 

 the Baltic countries, northern and northwestern Germany, and 

 the mountainous areas of middle Europe (cold windy valleys of 

 the pre- Alps and cold moist Jura heights in Switzerland) ; (4) 

 wood-moss moor. Sphagnum fuscum Hochmoor, with Pinus 

 silvestris, Ledum palustre, Sphagnum an gusti folium, in eastern 

 Sweden, Poland, Finland, Russia — in all the less oceanic areas. 



20.Siccideserta: Dry deserts. — ^These are open communities. 

 Larger plants do not exert any marked influence on any lower 

 story which may be present. They are conditioned by the dryness 

 of the climate. They lie in the great subtropical high-pressure 

 zone of the earth. Temperatures may be hot or cold; the low 

 amount of precipitation and its irregularity are decisive. Great 

 deserts are the Eurasian, North African, western American, 

 Australian, and South African. 



Artemisia steppes: The Caspian (Asia) Artemisia scrub desert 

 includes an Artemisietum maritimae incanae and, in saltier 

 dales, Artemisietum pauciflorae. Well known are the extensive 



