VEGETATION OF THE MARSH AND BOG 245 



duced is insufficient to exert much influence on the 

 vegetation. The consequent absence of well-marked 

 xerophytes forms one of the chief distinctions between 

 the marsh-flora and that of the bog. 



The water of the marsh comes from a wide area, and 

 in the neighbourhood of streams is being constantly 

 replenished, so that plenty of nutritive material is present. 

 The well- nourished plants are quick-growing and tall, and 

 the general aspect of the vegetation differs considerably 

 from that of the bog, where the plants are slow-growing 

 and dwarfed. The difference is weU seen in plants which 

 grow in both marsh and bog — -e.g., the purple moor-grass 

 (Molinia ccerulea), which grows to a height of 4 to 5 feet 

 in Fenland marshes, but rarely reaches 2 feet when growing 

 in bogs. 



The vegetation is often of a very mixed character, 

 broad- and narrow-leaved plants growing indiscriminately ; 

 but occasionally a narrow-leaved form becomes dominant, 

 and gives rise to a pure association. Thus associations 

 dominated by Molinia ccerulea, Phragmites communis, 

 Cladium Mariscus, J uncus obtusiflorus, and other rushes, 

 or various species of Gar ex, are to be met with. Other 

 plants commonly found are : Ranunculus scderatus, 

 Caltha palv^tris, Viola folustris (marsh-violet), Stellaria 

 uliginosa (marsh-stitchwort), Hypericum tetrapterum and 

 H. quadrangulum (marsh St. John's- wort), Gomarum 

 paiustre (marsh-cinquefoU), Parnassia palusfris (grass of 

 Parnassus), various species of Epilobium (willowherbs), 

 Hydrocotyle vulgaris (marsh penny-wort), Valeriana dioica 

 (marsh-valerian), Gampanula (Wahlenbergia) hederacea 

 (ivy-leaved bell-flower), Anagallis tendla (bog-pimpernel), 

 Samolus Valerandi (brook-weed), Menyanthes trifoliata 

 (bog-bean), Pedicularis palu^tris, Orchis latifolia (marsh- 

 orchid), Iris, Triglochin palustre, Osmunda regalis (royal 

 fern), various species of Equisetum and EriopJiorum 

 (cotton-grass). 



Small areas of raised ground frequently occur in a 

 marsh, and on these drier parts a different type of vegeta- 

 tion exists. Many of the plants of the river-bank occur 

 (see list on p. 241), together with water-loving plants, 

 like Phragmites, whose deep-seated rhizomes are situated 

 in the wetter ground below. 



In many parts, as in the Fen district, the marsh may 



