INTRODUCTION 7 



found in moist woods on rocks, trees, old logs, etc., not 

 infrequently growing with mosses. 



The true liverworts {Marchantiales) do not have a 

 true stem or leaves, but are broad and flat, and cling 

 closely to the substratum. They are less frequently 



Liverwort (Marchanlia) Scale Moss i^azzania) 



HEPATICS 



confused with mosses. It is in regard to the leafy liver- 

 worts, or ''scale mosses" (Jungermanniales) , that one 

 particularly needs a word of warning. 



The scale mosses have leafy stems and are pros- 

 trate, ascending, or erect. The leaves are usually 

 rounded, lobed, or cleft, often curved under at the tips, 

 and never have a midrib. There are two rows of leaves, 

 one on each side of the stem, with a third row of modi- 

 fied leaves underneath; so that the plants are not only 

 flattened, but have also two distinct surfaces. This 

 flattened appearance of the stems and the peculiar 

 shape of the leaves are good distinguishing character- 

 istics that separate these hepatics from the mosses. 

 The leaves of mosses are never lobed or cleft, and are 

 usually arranged all around the stem, so that the 



