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 well seen in plants which 
grow in both marsh and bog—e.g., the purple moor-grass 
(Molinia cerulea), 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 cerulea, Phragmites communis, 
Cladium Mariscus, Juncus obtusiflorus, and other rushes, 
or various species of Carex, are to be met with. Other 
plants commonly found are: Ranunculus  sceleratus, 
Caltha palustris, Viola palustris (marsh-violet), Stellaria 
uliginosa (marsh-stitchwort), Hypericum tetrapterum and 
H. quadrangulum (marsh St. John’s- wort), Comarum 
palustre (marsh-cinquefoil), Parnassia palustris (grass of 
Parnassus), various species of Epilobiwm (willowherbs), 
Hydrocotyle vulgaris (marsh penny-wort), Valeriana dioica 
(marsh-valerian), Campanula (Wahlenbergia) hederacea 
(ivy-leaved bell-flower), Anagallis tenella (bog-pimpernel), 
Samolus Valerandi (brook-weed), Menyanthes trifoliata 
(bog-bean), Pedicularis palustris, Orchis latifolia (marsh- 
orchid), Iris, Triglochin palustre, Osmunda regalis (royal 
fern), various species of Hquisetum and Eriophorum 
(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 
