268 



PRACTICAL BOTANY 



is atmospheric contact with the internal chlorophyll region. 

 The lower layers of tissue bear less chlorophyll, but they com- 

 pose the main supporting part of the plant. From these the 

 rhizoids descend. In vegetative structure Marchantia is more 

 complex than Riccia, or perhaps than mosses, and very much 

 more complex than any of the green algae. 



FIG. 223. A common liverwort (Marchantia) 



The plant shown at the left is an archegonial or female plant : rh, rhizoids ; c, cupules, 

 in which are buds or gemmae ; s, stalk of the archegonial branch ; r, radiating, 

 finger-like projections of the head ; a, region in which the archegonia are borne. 

 At the right is an antheridial plant : a, antheridial head. Both plants show the leaf- 

 like expansion (I) and the midrib (m) . About one and one-half times natural size 



250. Marchantia: vegetative reproduction. Upon the upper 

 surface of Marchantia in the midrib region there are frequently 

 developed cup-like outgrowths (cupules), within which many 

 buds (gemmce) are formed (Fig. 223, <?). The gemmae grow 

 upon small stalks from the bottom of the cupules. In a given 

 cupule there may be gemmae ranging in size and age from 

 those that consist of one or a few cells to those with dozens 



