COMMON LIVERWORT. 

 Marchantia polymorpha L. 



PRELIMINARY. 



THIS plant is common throughout America and 

 Europe. It grows among grass, over wet soil or 

 rocks, in dryer spots along walls and fences, and occa- 

 sionally in more exposed situations, but is most luxu- 

 riant in damp shady places. The vegetative part con- 

 sists of flat, green, leaf-like stems, twelve millimeters 

 (half inch) or so wide and five to eight centimeters 

 (two or three inches) long, appressed to the ground, 

 held down by numerous silky hairs on the under side, 

 and much branched, usually forming extended mats. 



There are two sorts of reproductive branches which 

 occur on separate plants. These branches (see fig. 2) 

 are slender stalks about an inch high, bearing flat disk- 

 like heads a quarter of an inch or more across the 

 male with scallops, the female with finger-shaped rays. 

 The two forms sometimes grow at the same spot or 

 locality, but quite as often entirely apart from each 

 other. Besides these organs there are often small 

 sessile cups (cupules) on the upper surface of the stems, 

 containing green grains. 



If either cupules or reproductive branches are present, 



