BRYOPHYTES 
loi 
(2) JUITCERMANNIALES 
General character. This is by far the largest group of liverworts, its 
members living in all conditions of moisture from very wet to very dry. 
They are especially abundant in tropical 
forests, being very common on the bark of 
trees (epiphytic) and on leaves (epiphyllous), 
while some grow on the ground. Two great 
groups are recognized : (i) thallose forms, 
whose gametophyte body is a thallus resem- 
bling that of the Marchantiales in general 
outline (see fig. 777); (2) foliose forms, with 
leafy bodies (fig. 235). However, there is FK. 231. Pell. thallus 
, , . - .u 11 t_ j- bearing a sporophyte with 
complete gradation from thallus bodies, Iong seta (indicating a]so 
through those whose thallus is more and position of archegonium) ; 
more deeply lobed, to those in which the the black dots on the older 
... ,. . . portion of the thallus in- 
lobes have become distinct leaves. ^^ antheridia . 
The most essential distinction between the 
two groups is based upon the position of the archegonia, which of 
course involves the position of the sporophytes. In the thallose forms 
the archegonia are on the dorsal surface of the thallus (figs. 231, 232); 
and on this account they are 
called the Anacrogynae, mean- 
ing archegonia not at the apex. 
In most foliose forms the apical 
celt becomes an archegonium 
initial; and on this account they 
are called Acrogynae, meaning 
archegonia at the apex (fig. 235). 
The acrogynous Jungerman- 
n j ales are knQwn commonly as 
the leafy liverworts, or some- 
times as scale mosses. 
In contrast with the Marchantiales, the Jungermanniales show very 
little differentiation of the tissues of the gametophyte; but they show 
very great differentiation in the form of the gametophyte. 
(a) Anacrogynae 
Gametophyte. The gametophyte of the simplest Anacrogynae, 
such as Aneura and Pellia, are the simplest gametophytes known among 
FIG. * 3a .-Symphyogyna: thallus showing 
lobed margin and bearing two sporophytes on 
its dorsal surface. 
