LEAFY LIVERWORTS 



123 



The commonest species, F. dilatata (Fig. 32 and Plate), grows on 

 tree trunks, especially smooth-barked ones like beech and holly, 

 forming patches which are usually purplish in colour. Each 

 side-leaf is deeply 

 divided into two 

 lobes, the large 

 upper lobe being 

 large and roughly 

 circular, while the 

 lower forms a neat 

 little cup or 

 pitcher. The 

 pitchers are closely 

 pressed to the tree 

 trunk, and besides 

 storing water often 

 contain small 

 animals (wheel 

 animalcules, insect 

 larvae, etc.) which 

 have come in for 

 shelter. It has 

 been supposed that 

 these organisms 

 are captured and 

 digested by the 

 liverwort, but this 

 is doubtful. An- 

 other kind, Radula 

 complanata (Fig. 

 33), also found on 

 tree trunks, has 

 the lower leaf-lobe 

 folded upon the 

 larger upper lobe, forming a kind of water pocket, and also bearing 

 the rooting hairs. In a few cases the lower lobe of the leaf is larger 

 than the upper (Diplophyllum, Fig. 34, A ; Scapania, Fig. 34, B), 

 the two lobes being folded on each other. In others still, the 



FIG. 35. Lepidozia^ a leafy liverwort. The larger drawing 

 shows the upper side, the smaller one the under side. 



