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shoots into the air (see Text-fig. 11). The “ wet plants ” which have 
creeping stems, and stiff pointed shoots that can easily force their 
way up through the overlying soil &c., are those best adapted for this 
invasion of the drier areas. It is generally such plants, e.g. 
Phragmites and jfuncus obtusifiorus, that one actually finds in these 
cases. The “ dry plants ” on the other hand, are much more rarely 
able to endure the conditions found in the wetter parts of the 
marsh. A reciprocal invasion does occur, however, and will be 
described later in this paper. 
Thus the wettest parts of the Fen are occupied only by “ wet 
plants ” ; the drier parts chiefly (though not exclusively) by “ dry 
plants ” ; while the intermediate places, where the average water 
level is, say five inches or more below that of the soil, may contain 
a complicated mixture of wet, intermediate and dry forms. In the 
latter case the underground parts are adjusted at different levels 
according to the idiosyncrasies of the plants themselves. 
The underground parts hitherto mentioned have been chiefly 
stems, but the roots also require some mention, Speaking generally, 
there is a marked tendency for the roots of the Fen plants to be 
placed more or less horizontally in the soil (Text-figs. 12, 13 and 14). 
This may apply in the case of Dicotyledones, to the primary as well 
as the lateral roots (e.g. Peucedanum palustre, Text-fig. 13). “ Dry 
plants” living in a relatively damp soil exhibit this tendency to a 
very high degree, their roots often creeping amongst mosses, &c., 
actually on, or only partly beneath the surface. But “ wet plants ” 
also frequently show a similar method of root growth, e.g. Cladium 
(Text-fig. 12). The direction of growth of the roots would seem to be 
