172 A TEXT-BOOK OF 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 odspore, as is common 
among the Thallophytes, but the spore-case or sporophyte. 
97. Other Marchantia forms.—Associated with .archan- 
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- 
Fic. 168.—Jungermannia forms: A, thallose form; monly mistaken for 
B, leafy form. WOSeeR. 
The common name of the group suggests one of its 
principal features. The lowest forms have a very simple 
thallus body (Fig. 168, 4); but in most of the forms the 
body consists of a central stem-like axis bearing two rows 
* In case either Mreciocarpus or Riccia can be obtained, it should be 
studied rather than Afarchantia, 
