CHAPTER XIX 
THE BRYOPHYTES 
This interesting group, comprising the second division of the 
Vegetable Kingdom, is represented by the liverworts and the 
mosses. These plants show a beginning of definite alternation of 
generations, 7.¢., gametophyte (sexual_phase) alternating with _ 
sporophyte (asexual phase of development) i in their life history, the 
two phases being combined in one plant. The sporo _Is 
attached to the gametophyte throughout its existence, being 
parasitic upon rit. Of the two Pp hases, the. gametophyte i iS always 
the larger. r and more conspicuous structure. ‘The female sexual 
cell is always lodged in an archegonium (a multicellular female 
sexual organ). 
There are two classes of Bryophytes: Crass I, Hepatic 
or liverworts and Cass II, Musci or mosses. 
HEPATIC2 OR LIVERWORTS 
The liverworts are a class of aquatic or terrestrial plants 
occurring in tropical and temperate regions. While most of 
them live in_ moist land situations, some are found submerged or 
floating in water, some are epiphytic, and others occur in localities 
where long dry seasons prevail. The body of a liverwort either 
consists of (1) a small, flat, dichotomously branching thalloid 
body showing differentiation into a green upper or dorsal region 
and a nearly colorless under or ventral part, as in Riccia or 
Marchantia, or (2) of a branching stem which bears two rows of 
dorsal leaves containing chloroplasts and one row of pale ventral 
leaves, as in Porella and other higher liverworts. Reproduction 
is by fertilization or by vegetative multiplication. Some species 
develop both kinds of sexual organs (antheridia and archegonia) 
on the same gametophyte and so are monecious, while others 
develop antheridia on one gametophyte and archegonia on 
another gametophyte and are therefore diwcious. 
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