272 ESSENTIALS OF BOTANY 
fi of aquatic plants, and water 
is absolutely necessary to ac- 
complish fertilization. 
Some liverworts are mi- 
nute floating plants (Fig. 
188) much simpler than Mar- 
chantia, others are terrestrial, 
of more complex organization than Mar- 
chantia. Many of the higher liverworts 
(Fig. 195) have leafy stems and in appear- 
ance slightly resemble the mosses. 
MNIUM, A COMMON MOSS?! 
351. Occurrence. — Mnium cuspidatum is 
a very widely distributed moss occurring 
abundantly on shaded ground and espe- 
cially about the bases of trees in open 
woods. It may be known by the yellow 
or light brown ellipsoidal capsule, which is 
attached, at right angles or slightly droop- 
ing, to a slender stalk about an inch long. 
The leaves of the vegetative branches are 
round-obovate and pointed by a minute pro- 
longation of the midrib. They have minute 
sharp teeth and, in fresh moist material, are 
pale green. The capsules are produced in 
Moss (Siphay- the spring, and material showing various 
num). stages of development should be collected. 
Fic. 197. Peat- 
1 Any of the common mosses, Bryales, will answer for this study. Atrichum 
angustatum is of frequent occurrence in woods and on sandy hills. Funaria 
hygrometrica is common on bare ground and especially on burnt-over places. 
Two species of Bryum are widely distributed, and Polytrichum commune, a 
very large moss, is found abundantly in open woods and pastures in the north. 
