38 THE BOOK OF NATURE STUDY 



place. It is in the peat area that the characteristic Fen plants 

 are found ; whilst in the silt land there will be plants of a more 

 or less maritime character. The Fen plants should be looked 

 for near the ditches. The dominant species will probably be 

 found to be the Sedge, Cladium germanicum ; but this is some- 

 times ousted by one of two Grasses, Molinia ccerulea, which, as 

 already noticed, is characteristic of wet moors, or Phragmites 

 communis. Where the ground is subject to frequent flooding 

 the Phragmites ousts both the Molinia and the Cladium ; on the 

 other hand, if flooding occurs but rarely, the Cladium drives out 

 the Phragmites. Other plants belonging to what may be called 

 a Phragmites, or a Cladium association, are : The Yellow Meadow 

 Rue, the Marsh Marigold, the Larger Convolvulus, and the Marsh 

 Pea. The Yellow Meadow Rue grows from two to four feet high, 

 and has, like the Ranunculacese generally, numerous stamens 

 with yellow anthers, which make the flower conspicuous, as there 

 are no petals and only small sepals. The Convolvulus and the 

 Marsh Pea are climbing plants that make use of the Sedges and 

 Grasses as support, matting the whole together into a luxuriant 

 mass of vegetation. The Convolvulus climbs by means of its 

 twining stem, the Marsh Pea by tendrils. The Larger Convolvulus, 

 the species belonging to the Fen ditches, differs from the Bind- 

 weed in having no scent. The flower remains open on moonlight 

 nights, and is pollinated by the Convolvulus hawkmoth ; it seldom 

 sets its seeds where that does not occur. The shade formed by 

 these plants is so dense that certain Ferns and Liverworts are 

 usually found sheltering under them. 



THE VEGETATION OF RUNNING WATER. In the ditches 

 intersecting the rough meadows of the Fen country, where water 

 runs but slowly, three plants are usually found, the Greater Spear- 

 wort, the Small Bur- Reed, and the Sedge (Car ex Pseudo-cyperus) . 

 All these plants have more or less grass-like leaves, and it will be 

 found that plants adapted for life in running water usually have 

 upright aerial leaves, which enable them to stand the flow of 

 the water and the rush, often considerable in time of floods. 

 This type of leaf is more usual in monocotyledons than in dicoty- 

 ledons, the parallel veins of monocotyledonous leaves suit the 



