236 



MORPHOLOG Y. 



side. It does not matter on what side they lie, for whichever side it is, that 

 will develop into the lower side of the thallus, and forms rhizoids, while the 

 upper surface will develop the stomates. 



Leafy-stemmed liverworts. 



496. We should now examine more carefully than we have 

 done formerly a few of the leafy-stemmed liverworts (called 

 foliose liverworts). 



497. Frullania (Fig. 32). This plant grows on the bark of 

 logs, as well as on the bark of standing trees. It lives in quite 



dry situations. 

 If we examine 

 the leaves we 

 will see how it is 

 able to do this. 

 We note that 

 there are two 

 rows of lateral 

 leaves, which 

 are very close 

 together, so 

 close in fact that 

 they overlap 

 like the shingles 

 on a roof. 

 Fig. 260. Then, as the 



Section of thallus of marchantia. A , through the middle portion ; 

 B, through the marginal portion ; /, colorless layer ; chl, chlorophyll Creeping Stems 



layer; sp, stomate; A, rhizoids; b, leaf-like outgrowths on under 

 side (Goebel). 



lie very close to 



the bark of the tree, these overlapping leaves, which also 

 hug close to the stem and bark, serve to retain moisture 

 which trickles down the bark during rains. If we examine 

 these leaves from the under side as shown in fig. 34, we see 

 that the lower or basal part of each one is produced into a 

 peculiar lobe which is more or less cup-shaped. This catches 

 water and holds it during dry weather, and it also holds moisture 

 which the plant absorbs during the night and in damp days. 



