230 



HALOPHYTES sect, vii 



height and present a dull, bluish appearance ; at the blossoming season 

 the scaly thin branches become decked with countless small, bright-red 

 flowers. 



As halophytes are so xerophytic in structure, it is not surprising 

 that growth-forms of the one type of vegetation reappear in communities 

 belonging to the other type. For example, in Venezuela and the West 

 Indies, on the shore, intermingled with Batis, Sesuvium, and other true 

 littoral plants, one finds certain Cactaceae, and Bromehaceae that are not 

 halophilous in the strict sense. According to Schimper, in Java alpine 

 plants recur in saline, moist spots ; and Battandier discovered a floristic 

 likeness between the littoral and alpine floras of Algiers. 



CHAPTER LVIII. PELOPHILOUS HALOPHYTES 



a. Aestuarium with Zosteretum and Salicornietum. 



Zosteretum. Where the saline soil is loamy and contains clay there 

 appear species of plants and, to some extent, formations differing from 

 those on pure sand ; and in this case, again, the distribution of the species 

 as well as of the associations is zonal. The North-European shores 

 provide admirable illustrations of this. Special reference may be made 

 to the marshy tracts on the eastern coasts of the North Sea. Here the 

 tide twice a day brings a quantity of extremely fine, organic, and inorganic 

 constituents, mainly clay, which are deposited in calm spots during 

 high tide. These constituents are held fast and filtered, in the first place, 

 by grass- wracks (Zostera), which form large, mud-collecting banks 

 (zostereta), and, in the second place, in shallower water by Cyanophyceae 

 and by Salicornia herbacea. The Cyanophyceae form a zone parallel to 

 the Sand-Algae-formation on the sand of the shore ; they also appear 

 in zosteretum, and may cover the soil of salicornietum and of true littoral 

 meadow.i 



Salicornietum. Salicornia herbacea produces a pure but very open 

 association (salicornietum), which forms the outermost zone of true land- 

 vegetation (formation of halophilous herbs) ; it clothes large stretches 

 of the beach where this is not covered by water at low tide, and it is 

 under water at high tide, although it is a cactus-hke, succulent plant, 

 and apparently a pronounced xerophyte. Being devoid of foliage its 

 fleshy stem has undertaken the work of assimilation,^ and possesses 

 a two-layered palisade tissue sharply cut off from the internal aqueous 

 tissue, and in addition contains tracheid-hke cells that store water .^ 



b. Salt-meadow. 



Glyceria mantima-association, in North Europe. When the soil has 

 become higher and drier, owing to the deposit of mud year after year 

 between the annual salicornias, it is occupied by Glyceria maritima- 

 association (Festuca thalassica-association). This plant, with its narrow- 

 leaved glaucous shoots, which bend aside just above the soil and bear 



^ Warming, 1904, 1906. 



" Dangeard's (1888) interpretation of the succulent portion as a foliat sheath is 

 maintained by others. * See p. 126. 



