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VEGETATIONAL TYPES OF TROPICAL LANDS 



461 



free water accumulates on the surface for some period or periods of 

 the year. Here, as in temperate regions, there is often a luxuriant 

 development of largely erect monocotyledonous plants, such as 

 Papyrus {Cyperus papyrus) or species of Reed {Phragmites) or Cattail 

 (Typha). These form characteristic reed-swamps, with roots under 

 water or in saturated soil, and with shoots extending more or less 

 high into the air. Whether the inundation is permanent or periodic, 

 and regardless of the water-level being relatively stable or fluctuating, 

 such swamp-plants typically contain air-passages for the aeration of 

 their roots and other covered parts. 



Fig. 160. Coconut Palms along a tropical sea shore. 



In many cases, particularly in the warmer regions, the shallow 

 water is colonized bv shrubs or trees, which may have special aerating 

 roots after the manner of mangrove types. Swampy grounds in both 

 the Old and New World tropics are frequently occupied by almost 

 pure stands of certain species of Palms, while even where the forest 

 is mixed it is usually much less rich in species, and particularly in 

 large tree species, than on drier land. These swamp-forest trees 

 usually, but not always, belong to species not normally found in 

 the surrounding forests. They are said in some instances, for 

 example in Burma, to be bare of leaves at the height of the rainy 

 season, when they stand in a metre or more of water. Like tropical 

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