60 COMMON LI VER WOR T. 



a. The branches ; all lying in the same plane as the 

 main axis, except 



b. The fruiting branches, consisting of erect stalks, 

 pedicels, supporting disk-like heads or receptacles 

 of two sorts, to be found on separate plants : 



i. The antheridial (sterile) with scalloped heads, 



and 

 ii. The archegonial (fertile) with star - shaped 



heads. 



2. The numerous hairs on the under surface of the thallus. 



3. The dark brown or purple leaves, somewhat concealed 

 by the hairs, and closely overlapping to form a low 

 ridge along the median line beneath. 



4. The scales along the sides of the thallus beneath, 

 some projecting beyond the margin ; more conspicu- 

 ous on plants grown in damp shady places. 



5. Sessile cups or cupules (very prominent when present), 

 seated on the upper surface of the thallus, containing 

 bright green flat bodies, the gemmae. 



B. THE STEM. Note 



1. The color of the upper and lower surfaces in fresh 

 specimens. 



2. The well marked median line, midrib ; and the broad 

 expansions, wings, on either side of it. 



3. The indented apex. 



4. Mode of branching, dichotomous ; each stem is resolved 

 into two equally diverging stems, one of which soon 

 exceeds the other by more rapid growth, giving the 

 false appearance of being monopodial. 



5. On the upper surface the small areas, areolae, best 

 seen on the older parts, in the center of each of which is 



