272 ESSENTIALS OF BOTANY 



of aquatic plants, and water 

 Sv ^ -." ^'i'A^s, is absolutely necessary to ac- 



complish fertilization. 



Some liverworts are mi- 

 nute floating plants (Fig. 

 -'4 188) much simpler than iMar- 



; I chantia, others are terrestrial, 



J of more complex organization than Mar- 

 chantia. Many of .the higher liverworts 

 (Fig. 195) have leafy stems and in appear- 

 I ance slightly resemble the mosses. 



MNIU.M, A CO:WMON MOSS ^ 



351. Occurrence. — Mnium cxspidatum 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 



'"J'r la i,^^'" the spring, and material showing various 

 Moss {Sphag- i fe' o 



num). stages of development should be collected. 



1 Any of the common mosses, Bryales, "will answer for this study. Alrichum 

 aiir/uxtiiluiiL is of frequent occurrenoe in woods and on sandy hills. Fuiiaria 

 hygroinetrica is common on bare ground and especially on burnt-over places. 

 Two species of lirymii. are widely distributed, .and Puliitrir/iiim coiiiinune, a 

 very large moss, is found abundantly in open woods and pastures in the north. 



