FERNS AND MOSSES. 149 
in the same group. Not uncommonly the leaves immediately surround- 
ing a group of antheridia possess special shapes and colours. In the hair 
moss (Polytrichum), for example, a large variety of which grows in damp 
woods, these leaves are of a reddish or orange colour, and constitute 
what are often incorrectly called “ flowers of moss.” 
The sporophytes differ as to situation, since they depend upon the 
previous position of the archegonia, and there is considerable variation 
in the shape of the capsule and the nature of the peristome. The 
calyptra too is of variable nature. In the hair moss (Polytrichum) it is a 
conical cap made up of golden brown threads. 
Liverworts resemble mosses in many respects, but there is often no 
distinction between stem and leaf in the oéphyte, which then consists 
of a flat green thallus, from the under side of which numerous rhizoids 
grow out. The archegonia and antheridia may be borne on special 
branches, as in one fairly common form called Marchantia, where there 
are mushroom-shaped branches bearing antheridia on the under side of 
their tops, while there are other branches that bear archegonia in a 
corresponding situation, and somewhat resemble open umbrellas with 
projecting ribs. 
The sporophyte in a liverwort is not covered by a calyptra, and is 
devoid of lid and peristome. The capsule opens by splitting longi- 
tudinally into four valves, and contains a large number of elastic threads 
(elaters) which help to scatter the spores. 
PTERIDOPHYTES comprise ferns and a number of fern-like 
plants, among which the common horsetails (Hquisetum) are 
best known. As in bryophytes there is a well-marked alterna- 
tion of generations, but the sporophyte is here the dominant 
stage, and possesses well-marked stem, leaves, and adventitious 
roots. The odphyte is a small structure termed a “ prothallus.” 
Properly developed vascular bundles are present in the tissues 
of the sporophyte. 
We may take as examples of the group the bracken fern 
( Pieris aquilina) and the male shield-fern (Nephrodium filiz-mas). 
SPOROPHYTE. 
In a moss what is called the “moss plant” consists of the 
oOphyte alone, or the odphyte with one or more sporophytes 
imbedded in it. But in a fern the ‘‘fern plant” is the sporo- 
phyte. The stem is a rhizome (p. 26), which in the bracken is 
cylindrical, and runs horizontally some distance below the sur- 
face of the ground, but in the male fern it is oblique and close to 
the surface. In either case the rhizome is perennial, and con- 
tinues to grow in length, its older parts dying off as it does so. 
The leaves of bracken come off in two rows from the stem, 
and arise at some distance from one another, while in the male 
fern they have a spiral arrangement, and are crowded together. 
In both cases the vernation is czrcinate, 7.e., the young leaves are 
