Plant Communities of the World 283 



ly.Emersiherbosa: Etnersed swamp vegetation. — The domi- 

 nants in this community are marsh plants which root in water- 

 covered or saturated soil, but which have their leafy shoots above 

 the water surface sufficiendy stiff to hold themselves erect. Water 

 is an equalizing element, watery habitats are similar even in very 

 diflerent general climates; water plants are therefore ubiquitous 

 and their communities are similar in different countries. The 

 order of Molinietalia coeruleae consists of communities which 

 have their roots, but not yet the stems, in the water. They make 

 what are called sour meadows; agriculture gains litter. In the 

 Molinion federation the association of the pipe grass, Molinia 

 coerulea, is the most important; in the Parvicaricion, one counts 

 in Switzerland the Schoenetum nigricantis; Juncetum sub- 

 nodulosi, Caricetum lasiocarpae, the important widespread Cari- 

 cetum fuscae, the alpine Eriophoretum scheuchzeri, and the 

 alpine Trichophoretum caespitosi and pumili. The Phragmite- 

 talia are new-land builders, pond communities. Of the Magni- 

 caricion elatae by far the commonest is the Caricetum elatae 

 (others are the Caricetum inflatae and Caricetum vesicariae), 

 beautifully described in 1863 by Kerner as the "Zsombek" of the 

 Hungarian lowlands, and by Pound and Clements on the 

 Missouri, and by Schroter in Switzerland. Still more widely dis- 

 tributed is the Phragmition, with the Scirpeto-Phragmitetum 

 communis, well known in many countries, as, for example, East 

 Norfolk in England, and the enormous areas in the Danube and 

 Volga deltas. If the water contains NaCl, one finds on all sea- 

 shores similar communities, the associations Atriplicetum por- 

 tulacoidis, Juncetum maritimi, Glycerietum maritimae, and very 

 commonly Salicornietum herbaceae and Spartinetum. 



/S. Submersiherbosa: Submersed stvamp vegetation. — This 

 consists of macrophytic aquatic plants with submerged or float- 



