CHAP. LVIII SALT-SWAMP 233 



are mostly either dark-green and glabrous, or grey with a coating of 

 mealy, scaly, or felted hairs, or are blue-green with wax. Salt-steppe 

 remains green when all the surrounding vegetation has withered. Many 

 of the species are more or less shrubby, and have narrow, linear, or 

 spathulate leaves, or are aphyllous. 



On Euro-Asiatic salt-steppes one finds species of Anabasis, Hali- 

 mocnemis, Haloxylon, also of the asclepiadaceous Brachylepis, and 

 others. 



In North America, among others, the following Chenopodiaceae occur : 

 Sarcobatus Maximiliani (' pulpy thorn '), Atriplex canescens, Spirostachys 

 occidentalis, Salicornia herbacea, and Suaeda, some of which are shrubs. 

 The salt-steppes formed by these lie on the large plateaux west of the 

 Rocky Mountains for example, in the neighbourhood of the Great Salt 

 Lake of Utah. 



The Argentine salt-steppes (los Salitrales) are interspersed in the 

 Pampas and merge with these. Among the plants occurring only on 

 saline soil are Suaeda divaricata, Spirostachys patagonica, and S. vagi- 

 nata, Halopeplis Gilliesii, Niederleinia juniperoides, and Statice brasi- 

 liensis. 



Between salt-steppes and other steppes there are frequently very 

 gradual transitional types, because steppe-soil always contains some salt. 

 Salt-steppe also gradually passes over into salt-desert. 



CHAPTER LIX. SALT-SWAMP AND SALT-DESERT 



THE communities discussed in the preceding chapter grow in soil 

 that is, at least periodically, more or less dry. Still more laden with 

 water is the soil in connexion with the formations about to be described. 



Salt reed-swamp. Along many of the shores in northern Europe 

 there are muddy spots in inlets where the water is calm. In such places 

 there arise swamps entertaining either halophilous or salt-enduring 

 species, in the form of tall perennial herbs, such as Phragmites communis, 

 Scirpus Tabernaemontani and S. maritimus, all of which possess long, 

 creeping rhizomes and therefore may produce dense communities. Added 

 to these are other herbs, such as Aster Tripolium and Triglochin mariti- 

 mum ; while the wet or flooded soil is covered by Cyanophyceae and 

 bacteria. 1 This is a formation parallel with fresh- water phragmitetum 

 and scirpetum (S. lacustris). Similar salt reed-swamps occur in Spain 2 

 and elsewhere. They also present themselves in connexion with steppes 

 and deserts when water is present. According to Martjanov those in 

 Central Asia on the Altai Mountains are surrounded by a dense palisade 

 of Phragmites communis, which is several metres in height ; outside 

 this, on drier soil, grow Salicornia herbacea, Suaeda maritima, Taraxacum 

 collinum, Lactuca sibirica, Triglochin maritimum, Plantago maritima, 

 Glaux maritima, Atriplex litoralis, Aster Tripolium, and others, most of 

 which are familiar species belonging to the North-European flora. 



Here also may be placed the shotts and sebakh of North Africa, depres- 



1 Warming, 1906. * Wilkomm, 1852, 1896. 



