INTRODUCTION. 



|O many different kinds of plants are called mosses 

 that it may be well to clear the field by defining the 

 true mosses as distinguished from the other plants 

 popularly called mosses. 



The sea-weeds or marine algae are often known as 

 sea mosses, but no true moss grows in salt water. 



The moss which drapes the trees in swampy regions of the 

 South is not a true moss, but a flowering plant bearing flowers 

 and seeds like a rose or a geranium. 



Lichens are frequently confused with mosses, but they never 

 bear leaves and never are a bright green, but a grayish or 

 brownish green, rarely black or bright colored. The majority of 

 species consist of a flat thin body usually prostrate and closely 

 applied to the substance upon which the plant grows. The 

 " Reindeer Moss " is a lichen with shrubby hollow stems ; the 

 gray " moss " that hangs from the limbs of trees in Northern 

 swamps is also a lichen. 



The Hepaticse, or liverworts, are most closely allied to the 

 mosses and some species are difficult to distinguish from them. 

 In general, however, the liverworts consist of a flat expanded 

 body like a bright green lichen, or, if leafy, the leaves, which 

 never have a costa, are arranged in two rows on opposite sides 

 of the stem and often in the same plane, giving the plant a flat- 

 tened appearance unlike the great majority of mosses. In fruit 

 the capsule of the leafy forms opens by four valves instead of by 

 a lid as in the mosses. 



The terms used in describing mosses are fully defined and 

 illustrated in the glossary, and the student should make himself 

 familiar with the principal terms as early in his study of the 

 mosses as practicable. 



The beginner in the study of mosses should be content with 

 the study of well developed fruiting specimens. Sterile spec- 

 imens should never be attempted unless their genus is readily 

 recognizable from previous experience, or some marked pecul- 

 iarity renders recognition easy. Imperfect or non-fruiting mosses 



