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A TEXT-BOOK OP BOTANY 



phytes, but it is not definite and universal until the liver- 

 worts are reached. 



It is important to note that in this life-history the pro- 

 tected stage of the plant, that is, the stage which can endure 

 the winter, is not a heavy-walled oospore, as is common 

 among the Thallophytes, but the spore-case or sporophyte. 



97. Other Marchantia forms. Associated with Marchan- 

 tia are other liverworts that are much simpler, and which 

 are really better to study if they are available. They differ 

 in having thallus bodies thinner, and hence simpler, in 

 structure; in having the sex-organs directly upon the thallus 

 or embedded in it; and in having simpler and more easily 

 observed spore-cases or sporophytes.* 



98. Jungermannia forms. These are commonly called 

 the leafy liverworts, and they are by far the largest group 

 of liverworts. They grow in damp places; or in drier 



situations on rocks, 

 ground, logs, or tree 

 trunks; or in the 

 tropics on the leaves 

 of forest plants. 

 They are general- 

 ly delicate plants, 

 and resemble small 

 mosses, many of 

 them being com- 

 monly mistaken for 

 mosses. 



The common name of the group suggests one of its 

 principal features. The lowest forms have a very simple 

 thallus body (Fig. 168, A); but in most of the forms the 

 body consists of a central stem-like axis bearing two rows 



FIG. 168. Jungermannia forms: A, thallose form; 

 B, leafy form. 



* In case either Ricdocarpus or Riccia can be obtained, it should be 

 studied rather than Marchantia. 



