HYDROPHYTE SOCIETIES. 187 



of nearly reclaimed ponds may be noticed, where bulrushes, 

 cat-tail flags, and reed grasses still occupy certain wet 

 spots, but are shut off from further migration. The social 

 growth of these plants, brought about by extensive root- 

 stock development, is especially favorable for detaining 

 detritus and building a land surface. 



Reed-swamp plants also have in general a tall and un- 

 branched habit of body. They may be bare and leafless, 

 with a terminal cluster of flowers, as in the bulrushes ; or 

 the wand-like stems may bear long, linear leaves, as in the 

 cat-tails ; or the stem may be a tall stalk with two rows 

 of narrow leaves, as in the reed grasses. No more charac- 

 teristic group of forms is found in any society. Of course, 

 associated with these forms are also free and fixed hydro- 

 phytes, which characterize the other societies. 



138. Swamp-moors. — The word moor is used to designate 

 the meadow-like expanses of swampy ground. Here belong 

 the ordinary swamps, marshes, bogs, etc. There is less 

 water than in the case of the reed swamps, and often very 

 little standing water. One of the peculiarities of the 

 swamp-moor is that the water is rich in the soil materials 

 used in food manufacture, notably the nitrates from which 

 nitrogen is obtained for proteid manufacture. In such 

 conditions, therefore, the vegetation is dense, and the soil 

 is black with the humus derived from the decaying plant 

 bodies. 



Typical swamp-moors border the reed swamps on the 

 land side, and slowly encroach upon them as the reed 

 plants build up land. Probably the most characteristic 

 plant forms of the swamp-moor arc the sedges, and asso- 

 ciated with them are certain coarse grasses. These give 

 the meadow-like aspect to the swamp, although these grass- 

 like forms are very coarse. Along witli the dominant 

 sedges and grasses are numerous other plants adapted to 

 such conditions, such as some of the buttercups. It would 

 be impracticable to give a list of swamp-moor plants, as the 



