MARCHANTIA POLYMORPHA. 



BRYOPHYTES; HEPATIOE; MARCHANTIALES. 



PRELIMINARY. 



THIS liverwort is common throughout America and 

 Europe. It grows among grass, over wet soil or rocks, 

 in drier spots along walls and fences, and occasionally 

 in more exposed situations, but is most luxuriant in 

 damp shady places. The vegetative part consists of 

 a flat, green, leaf-like, dorsiventral body, on the under 

 side of which are rhizoids that hold it close to the ground. 

 Often the plants may be distinguished by the presence 

 of reproductive branches that arise as stalks from the 

 flat part of the main body, and bear expanded heads 

 at their upper ends. Besides these there are often small 

 sessile cups, the cupules, on the upper surface of the 

 stems. On the dorsal surface the plant is divided into 

 very small diamond-shaped areas. When the repro- 

 ductive branches and cupules are present Marchantia 

 may easily be recognized. Conocephalus conicus, another 

 liverwort that grows in damp places and bears a strong 

 general resemblance to Marchantia, may be distinguished 

 by its much more prominent diamond-shaped areas, and 

 the more prominent pore that is visible to the naked eye 



85 



