274 SUCCESSION IN EURASIA. 



With these occur many species of Carex (C. nvians, riparia, stricta, and leporina) , 

 Cyperus, Sparganium ramosum, and Typha. Where the reeds are sparse or 

 lacking, there develop distinct communities, often dominated by Heleocharis 

 palustris, with which occur Berula angustifolia, Oenanthe, and, more rarely, 

 Trapa nutans, Epilobium palustre, Solanum dulcamara, and Lycopus europaeus. 

 In other areas. Polygonum hydropiper, mite, persicaria, and lapathifolium, 

 Rumex pulcher, hydrolapathum, Roripa palustris, and R. amphibia are charac- 

 teristic. Throughout these areas free from Typha and Phragmites are found 

 Catabrosa aquatica, Glyceria plicata, Beckmannia eruciformis, and Alopecurus 

 genicidatus. The less important species complete the similarity with American 

 swamps, e. g., Acorus calamus, Veronica anagallis, Scutellaria galericulaia, 

 Stachys palustris, Rumex obtusifoliu^, etc. 



Herzog (1909) has distinguished two forest formations in Sardinia — ^the de- 

 ciduous forest of Castanea and Quercus and the coniferous forest of Juni- 

 perus oxycedrus and J. phoenicea: 



The macchia is regarded as a primitive and independent formation, not one 

 which has arisen out of the shrubby layer of cleared forest. Along the stream- 

 banks is found the formation of Nerium oleander. Many constituents of the 

 macchia appear also in the heath formation, which exhibits a large number of 

 communities. Closely associated with the heath is the rock-steppe formation. 

 In the formation of the dunes can be distinguished three stages: the open 

 Bteppe-like vegetation of the moving sand, the transition stage to scrub, and 

 the final stage of the stable dunes where the vegetation approaches that of the 

 neighboring macchia. Behind the dunes is to be found the salt-meadow 

 formation, which is separated with difficulty in many cases from the formation 

 of the saline and brackish swamps. 



DuceUier (1911) has studied the dunes of Algeria, dividing them into three 

 bands or zones: littoral, humid, and continental. The typical succession on 

 the dimes is the following: 



(1) Mobile dune: Silene colorata, Linum strictum, Ononis variegata, Rumex hucephalophorus. 



Euphorbia peploides, CtUandia marUima. 



(2) Intermediate dune: Lotus creticus, Scabiosa rutaefolia, Centaurea maritima. 



(3) Stable dune: Pislacia lentiscus, Olea europaea, PhUlyrea media, Pinus halepensis. 



TROPICS AND SUBTROPICS. 



Trevb (1888), after the destructive eruption of Krakatoa in 1883, foimd that 

 Cyanophyceae were the first plants to appear on the new soil. These were 

 followed by an exclusive vegetation of ferns, in which a few phanerogams, 

 especially composites, began to appear by the third year. 



Schimper (1891) has described the development of the four strand formations 

 in the Tropics. The mangrove formation is found on the coral-reefs and the 

 trees grow with their roots in pure sea-water. The Nipa formation (Nipa 

 fruticans) consists of palms growing in brackish water. The Barringtonia 

 formation, consisting of Barringtonia, Ca^uarina, Cycas, and Pandanus, grows 

 above the tide on the strand. The Pes-caprae formation {Jpomoea pes-caprae) 

 consists of scattered strand shrubs and bushes. 



Borgesen and Paulsen (1898) divide the vegetation of the Danish West 

 Indies into two groups — halophytic, and forest and scrub. The former con- 

 tains the sea-grass vegetation, vegetation of the sandy strand, with the 

 Pes-caprae and the Coccoloba-Manchinil formations, rock-coast vegetation, the 

 mangrove vegetation, and the saline vegetation of Batis, Salicornia, Sesuvium, 



