Wicken Fen. 
73 
frequent amongst marsh plants (Text-figs. 11, 12, 14 and 15). This 
leads, in the case of a practically closed “ formation ” such as 
Wicken Sedge Fen, to an almost inextricable tangle of roots, 
rhizomes, stolons, &c., just below the surface of the soil. 
Although in general the subterranean organs of marsh plants 
are placed comparatively near the surface, yet the depths at which 
these parts are buried may vary considerably. It depends in any 
given case partly on the species of plant, and partly on the water 
content of the soil. Thus the rhizomes, &c., of the more definitely 
wet-marsh plants may, if growing actually in shallow water, creep 
on the surface of the underlying mud. But if growing in the drier 
parts of the Fen, they are frequently placed at considerable depths 
in the soil. For instance, in the drier parts the rhizome of Cladium 
is generally found at a depth of six to nine inches (Text-fig. 12), and 
Text-fig. 12. Cladium Mariscus, in moderately damp soil (September). 
XI- 
that of Juncus obtusiflorus is often buried three to five inches (Text- 
figs. 11 and 15). A “wet plant” then, growing on a “ dry island,” 
can easily adjust itself by placing its rhizome at a lower level. To 
put it more correctly, the plants have probably become first 
established in the damper soil, and have subsequently crept into 
the drier parts by undermining them, and then sending up their 
