m^ 





.ife*». 









Figure 23. The dark area below the pencil is a liverwort ( Porella pinnata ) zone, the 

 upper boundary of which indicates that high water has stayed at that level for at least 

 16% of the year (58 days, not necessarily consecutive). The zone above it is a green 

 moss. The upper boundary of Porella growth is helpful for quickly determining depth 

 and duration of flooding. 





1^ 





y4t^ - .^■ 



Figure 24. The outermost swale (next to the upland) along the lower Roanoke River (NC) 

 supports almost pure stands of either swamp or water tupelo on black, muck soils. Here, 

 in a water tupelo stand, in response to the anaerobic muck, roots form blocky aerial 

 knees which resemble black rocks. 



49 



