INTRODUCTION 



SO many different kinds of plants are called mosses that it may 

 be well to clear the field by defining the true mosses as dis- 

 tinguished from the other plants popularly called mosses. 



The sea weeds or marine algee 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 of 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 (substratum). 

 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 Hepaticas, 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 are arranged 

 in two rows on opposite sides of the stem and in the same plane, 

 giving the plant a flattened appearance unlike the great majority 

 of mosses. In fruit the capsule opens by four valves instead of 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. Imperfect or 

 non- fruiting mosses often prove an insoluble puzzle to the ad- 

 vanced student and would be nothing but a source of discourage- 

 ment to the beginner. Many mosses of the more difficult genera 

 like Hypnum and Bryum are not included in this book because 

 they cannot be recognized with any degree of certainty without 

 the aid of the compound microscope. As some of these difficult 

 species are common they will prove a source of annoyance to the 

 beginner, and it is hoped will lead him to obtain, sooner or later, 

 the necessary books and apparatus for a more extended study. 



