330 
MOSSES AND THEIR ALLIES 
From this fertilized egg cell a sporophyte (spore plant) 
grows out of the archegonium. The sporophyte consists 
of a foot, a pad by which it gets its food from the gameto- 
phyte, the seta, a slender stalk, and the capsule or spore- 
case. While every mature gametophyte leads an inde¬ 
pendent existence, the sporophyte is a parasite. 
Thus in its life history the moss plant has two distinct 
generations, the gametophyte or sexual and the sporophyte 
which reproduces asexually (Figure 299), by spores! This 
is known as the alternation of generations. That is, a 
sexual generation produces an asexual generation and an 
asexual in turn produces a sexual generation. 
282. Economic Value. — Mosses have little economic 
value. In cold regions some kinds are dug from under 
the snow to be used as food for the reindeer. They are 
interesting as showing a stage of de¬ 
velopment of the flowering plants. 
LABORATORY STUDY 
Moss (Polytrichum). Study moss plants 
and note the difference in size between the 
male and female plants. Make a drawing to 
show the difference in size and in the arrange¬ 
ment of the leaves. Select a female gameto¬ 
phyte which has a sporophyte. Draw and label 
the seia or stalk, and the capsule, the box at the 
top. Look for moss plants on trees, along the 
edges of sidewalks, and on damp soil. With 
the microscope examine archegonia and an- 
theridia. Draw and label. When antheridia 
from fresh material are used, the sperms can 
usually be seen escaping from the antheridium. 
283. Marchantia. — Marchantia (mar-kan'tia) is a plant 
belonging to the moss group, which grows in very moist places. 
It has a thin, broad body or thallus (thal'lus : Greek, thallos, 
a young shoot), which is green on the upper surface and 
CHANTIA. 
Plant with archegonial 
branches. 
